5.2: Anna Freud and Ego Psychology
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Anna Freud (1895-1982) was the youngest of Sigmund and Martha Freud’s six children, and the only one to pursue a career in psychoanalysis. However, this did not come about immediately, and Anna Freud never attended medical school as her father had. Therefore, she was one of the first lay psychoanalysts, which is an important consideration for all mental health practitioners today (since Freud and most other early psychoanalysts were actually psychiatrists who had attended medical school). In 1971, a survey conducted among psychiatrists and psychoanalysts identified Anna Freud as the most outstanding colleague among both groups (see Peters, 1985).
Anna Freud lived with her parents until Sigmund Freud’s death in 1939. She was a lively child, with a reputation for being mischievous. Although she always enjoyed a good relationship with her father, it was her older sister Sophie who was her father’s favorite daughter (Peters, 1985). She was quite intelligent, but never attended college. She did, however, attend private schools, eventually entering the Cottage Lyceum in Vienna during fifth grade. She soon entered the Cottage Lyceum’s high school, graduating in 1912. Since she had not chosen a career, she traveled to England to improve her English, one of several languages she had learned. Upon returning to Vienna, she became a teacher at the Cottage Lyceum’s elementary school. She was very popular among her students, one of whom described her as “such a marvelous and simple figure that I loved her deeply at that time” (cited in Peters, 1985). Her popularity likely resulted from her own love of teaching and for her students (Coles, 1992). Anna Freud considered this experience as a teacher to have been very valuable for her later career as a child psychoanalyst:
The people who follow this line of thought hold that those who analyze children should possess not only the correct analytical training and mental attitude but something further: something which is called for by the idiosyncrasies of childhood, namely, the training and the mental attitude of the pedagogue… (pg. 130; A. Freud, 1973).
Even before she graduated, Anna Freud had begun reading her father’s works. But it was not until 1918 that she entered into psychoanalysis. Such a situation, a father psychoanalyzing his own daughter, would be considered inappropriate today, but at that time the entire field was still quite new and many aspects of it were still experimental. In any case, Anna Freud subsequently became one of her father’s most unwavering supporters and an important psychoanalyst in her own right. In 1920 she attended the International Psychoanalytical Congress with her father, and 2 years later she was a member of the Vienna Psychoanalytical Society and began presenting her own papers. In 1923 she began her own practice treating children.
As Anna Freud was developing her theories regarding the psychoanalysis of children, Melanie Klein was developing her theories in England. There were significant disagreements between them, including a symposium in 1927 organized specifically to provide an opportunity for Klein to publicly attack Anna Freud’s theories (Peters, 1985). After Anna Freud arrived to stay in England with her family in 1938, the conflict between them threatened to split the British Psychoanalytic Society. However, during World War II, a series of discussion forums resulted in the establishment of parallel training courses for the two groups.
After the war began, Anna Freud helped to set up the Hampstead War Nursery to provide foster care for over 80 children, a number that rose to a total of 190 children over several years (Peters, 1985). In addition to simply providing care for the children, she hoped to provide the children with continuity in their relationships with staff and family. With long-time friend Dorothy Burlingham she studied the effects of stress on young children in wartime. This work continued after the war when she had an opportunity to help provide care for six orphans who had survived the Theresienstadt concentration camp (Coles, 1992; Peters, 1985).
Throughout the rest of her life, she remained devoted to her work at the Hampstead War Nursery. She helped to establish the Hampstead Child Therapy Course (in 1947) and a children’s clinic. Eventually the nursery became known more simply as the Hampstead Clinic, and Anna Freud became one of the major figures in psychoanalysis. She often traveled to lecture in the United States, and in the 1970s she was a co-author, with two professors from Yale University, of two books about governmental involvement in the lives of children who have been emotionally deprived and socially disadvantaged (see below). She received many honors, including honorary doctorates from Clark University (where her father had lectured during his trip to America), Harvard University, and Vienna University. The honorary medical degree she received from Vienna University was awarded in 1972, only 1 year after she returned to visit her native city for the first time since the Freud’s had escaped the Nazis in 1938.
Shortly after her death, the Hampstead Clinic was renamed the Anna Freud Centre, in her honor, and in 1986 her former home became the Freud Museum. Although she has been considered by some to have done little more than continue her father’s work, she was a pioneer in both ego psychology and the psychoanalysis of children. Accordingly, she deserves to be considered one of the most influential neo-Freudians. Much of the information in this biography can be found on The Anna Freud Centre website, as well as much more information on the center itself ( http://www.annafreudcentre.org ).
Ego Psychology and the Defense Mechanisms
In 1936, Anna Freud published perhaps her most influential book: The Ego and the Mechanisms of Defense (A. Freud, 1936/1966). She began by stating a redefinition of the field of psychoanalysis. There was a general bias, in her opinion, among many psychoanalysts to focus on the deep instinctual impulses of the id at the expense of considering the ego. However, since the id is always unconscious, its processes can never be observed directly. It may also be difficult to observe the processes of the ego as well, but at least the ego exists partially within the conscious mind. Since it is the ego that observes both the impulses of the id and the restraints of the superego, and since the ego is available to the psychoanalyst, she concluded “this means that the proper field for our observation is always the ego.” (A. Freud, 1936/1966)
Although the ego is observable, that doesn’t mean that a person’s thoughts and behaviors always make sense. As the id demands the satisfaction of its impulses, the ego attempts to restrain the id, in accordance with the external demands of society and the internal representation of those demands in the superego. When these factors come in conflict, and the ego cannot easily resolve the conflict, anxiety develops. In order to help alleviate that anxiety, and to continue restraining the impulses of the id, the ego resorts to defense mechanisms. In so doing, the ego transforms the conflict somewhat and attempts to keep both the conflict and the basis for the conflict unconscious. When an individual is suffering psychologically and has sought help from a therapist, according to Anna Freud, the psychoanalyst arrives on the scene as someone who disturbs this fragile peace. This is because “it is the task of the analyst to bring into consciousness that which is unconscious…” (A. Freud, 1936/1966).
In order to understand how the ego uses defense mechanisms, it is necessary to understand the defense mechanisms themselves and how they function. Some defense mechanisms are seen as protecting us from within, from the instinctual impulses of the id (e.g., repression); other defense mechanisms protect us from external threats (e.g., denial). When treating a patient, the goal of the psychoanalyst is to determine how much a given defense mechanism contributes to the symptoms and to the ego resistance of the patient (in other words, resistance to therapy). To help understand these issues, Anna Freud identified and discussed ten defense mechanisms as being commonly recognized in the field of psychoanalysis: regression, repression, reaction-formation, isolation, undoing, projection, introjection, turning against the self, reversal , and sublimation. See Table 6.1 for a description of some of the defense mechanisms most commonly discussed today.
The defense mechanisms are not all available to an individual at the same time. As originally proposed by her father, Anna Freud believed that the defense mechanisms develop with the structures of personality (the id, ego, and superego). For example, projection and introjection depend on the differentiation of the ego from the outside world, so they would not be available to the ego as defense mechanisms until the ego had sufficiently developed (and, perhaps, differentiated into the superego as well; A. Freud, 1936/1966). This became an important point of contention, however, with the English school of analysis that included Melanie Klein. Whereas Anna Freud and her colleagues believed that projection and introjection would not be available in early childhood, since the structures of personality have not adequately developed, members of the English school believed that projection and introjection were a necessary part of that development. Although this debate and others between Freudian and Kleinian theorists became rather bitter (Mitchell & Black, 1995), Anna Freud did acknowledge the following:
These differences of opinion bring home to us the fact that the chronology of psychic processes is still one of the most obscure fields of analytic theory…So a classification of the defense mechanisms according to position in time inevitably partakes of all the doubt and uncertainty which even today attach to chronological pronouncements in analysis. It will probably be best to abandon the attempt so to classify them and, instead, to study in detail the situations which call for the defensive reactions. (pg. 53; A. Freud, 1936/1966)
The final outcome of personality development, whether primarily normal or abnormal, depends on the overall process of these defense mechanisms throughout development. It is natural that defense mechanisms are called upon by the ego during both waves of psychosexual development. Whether or not the ego develops as a yielding and flexible structure depends on the strength of the instincts during development and the environment in which the individual develops. If instinctual demands are excessively urgent during development, the ego will redouble its defensive activities. This can stiffen the resistance of the ego to the instinctual impulses, leading to symptoms and inhibitions that remain throughout life (A. Freud, 1936/1966). At least, they might remain until the patient is successfully analyzed by a qualified psychoanalyst.
What is the status of defense mechanisms in psychology today? Clinical psychologists have always found the concept of defense mechanisms useful, but for a period of time defense mechanisms did not receive much attention from academic psychologists (Cramer, 2000). The primary reason for this was that early studies aimed at demonstrating the existence of the defense mechanisms and their processes were not promising. However, these are particularly difficult processes to study, since much of the processing occurs unconsciously (Cramer, 2000; Kernberg, 2004). According to Cramer (2000), as the various fields of psychology developed, they began to examine psychological processes that received new names within the particular field, even though the processes being studied were actually defense mechanisms that had already been discovered within psychoanalysis. Just to cite a few examples: what cognitive psychologists describe as selective attention may involve the defenses of splitting and dissociation, in social psychology scapegoating is a form of displacement, and in developmental psychology a child’s verbal report of positive emotion while their facial expression clearly represents negative emotion is a classic case of denial (for a variety of examples and references see Cramer, 2000). Therefore, one can conclude that defense mechanisms, and defensive processes, have remained an important aspect of psychology and psychotherapy since they were first described by Sigmund Freud and Josef Breuer in 1895 (Freud & Breuer, 1895/2004).
Discussion Question: Anna Freud believed that even normal personality development involved the common use of defense mechanisms. Consider your own personality. Are there situations that make you anxious and, if so, can you recognize the defense mechanisms you rely on? Do you have a common defense mechanism that you use more than any other?
Psychoanalysis with Children
As mentioned above, Anna Freud began her career as a school teacher. This interest in children never diminished, and as she began to devote her career to psychoanalysis and psychoanalytic research her focus remained on the psychological lives of children. In 1946 she published The Psycho-Analytical Treatment of Children (A. Freud, 1946). This book is a collection of works she had written mostly in 1926 and 1927, with the final portion having been written in 1945. The book begins with an interesting preface, an apology that the book had not been available in English at an earlier date, particularly in the country of England. The reason for this, according to Anna Freud (and many historians agree), is that in England the theories of Melanie Klein dominated the psychoanalytic community (see also Mitchell & Black, 1995). Klein and her colleagues believed that psychoanalysis could be conducted successfully with young children, and that the process of transference occurred in the same manner as it did with adult patients. Initially, Anna Freud believed that psychoanalysis could not be performed with young children. Later, she acknowledged that the efforts of her colleagues had helped to make that a possibility, but she steadfastly denied that she had ever seen the normal process of transference in anyone younger than adulthood (A. Freud, 1946).
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Table \(\PageIndex{1}\): Common Defense Mechanisms |
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Repression |
Repression involves blocking an impulse from conscious expression. Examples include forgetting a traumatic event, such as sexual abuse, or being unaware of hostile feelings toward family members. |
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Regression |
When faced with difficult situations that we cannot resolve, we may regress to behavior indicative of an earlier stage of development. For example, when we are very sick, we may act as helpless as if we were an infant and hope that someone will take care of us. |
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Denial |
Denial refers to simply refusing to believe an unpleasant reality. For example, when someone is told they have a terminal illness, they may deny it and refuse to follow treatment recommendations. |
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Projection |
Projection involves attributing our own negative impulses to another person. If, for example, we want to see another person fail, perhaps to make us feel superior, we may claim that they are trying to interfere with our success. |
| Reaction-Formation | A reaction-formation is the process of suppressing unacceptable impulses and adopting an opposite course of action. For example, a parent who resents having children may shower them with love. |
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Identification |
We often model our behavior after people we admire, or adjust our behavior based on people we fear. Internalizing this process of identifying with others is primarily how the superego develops, how we adopt the rules and guidelines of our culture and make them our own. |
| Displacement | Sometimes we cannot respond directly to unpleasant situations, so we displace (or transfer) our impulses onto another object. For example, if your boss yells at you at work, you then go home and yell at people in your family. |
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Rationalization |
Rationalization is the process of finding logical reasons for unacceptable behavior or thoughts. For example, a professor may constantly battle with administrators about policies, while claiming that he/she only has the best interests of their students in mind. |
| Isolation | Isolation involves separating the anxiety-provoking aspects of an event from one’s other thoughts and behaviors. For example, following the death of a child, one parent may set aside their grief in order to be able to provide support for the other parent. |
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Sublimation |
Sometimes referred to as the successful defense mechanism, sublimation is the process of channeling unacceptable impulses into socially acceptable forms. It is often said that great artists must suffer before they can find the inspiration to master their craft. |
The importance of the analysis of children in terms of research is threefold, according to Anna Freud. It helps to confirm the theories develop by Sigmund Freud and others based on the analysis of adults, it leads to fresh conclusions and new conceptions (and she commends Melanie Klein on this point), and it serves as a point of transition to a field of applied analysis that she felt might become the most important of all: working with children as they develop (A. Freud, 1927/1973). What Anna Freud tried most to do in her writings was to point out the circumstances that make psychoanalysis with children different than psychoanalysis with adults. Fundamentally, there is no difference in the process. However, the results of the process must be viewed differently in order to understand what happens with children. Since Melanie Klein was actively pursuing the same goals, Anna Freud often wrote specifically about Klein, acknowledging her accomplishments, but also pointing out their differences.
The basic argument was aimed at the intellectual and psychological abilities of young children, and the extent to which the psychical apparatus (the id, ego, and superego) have developed. Since all three personality structures have developed in an adult, there is no need for the analyst to worry about that. All the analyst needs to do is to bring into consciousness the neurotic processes that have led to the patient’s symptoms (granted, that may be easier said than done). In children, however, the ego and especially the superego are still developing. Therefore, the analyst must consider the role he/she may play in the development of the child. The analyst must consider the extent to which the superego has already developed, and the analyst may be able to take advantage of its continuing development and help to direct and/or instruct superego development. According to Anna Freud (1927/1973):
…In the analysis of the adult we are at a point where the superego has already established its independence - an independence which is unshakable by any influence from the outside world...But child analysis must include all those cases in which the superego has as yet not reached any true independence. Only too clearly it strives to please its taskmasters, the child’s parents and others responsible for his training…we have to use our influence from without in an educational manner by changing the child’s relation to those who are bringing him up… (pgs. 138-139)
As these processes are actually observed, Anna Freud believed that the child’s symptoms could transform in the presence of the psychoanalyst, in a way that simply did not happen with adults. Thus, it was essential to observe children from a different point of view than one observes adults. She acknowledged that Melanie Klein had contributed to our understanding of how children might be observed, but she felt that Klein had attributed too much to what Klein and her colleagues observed. Klein allowed children the opportunity to play with toys in her office, a situation in which the child’s imagination can run wild. Klein believed this was the same for a child as free association was for an adult. However, Anna Freud countered that an adult is aware of their goals in psychoanalysis, whereas a child at play is not aware of being in therapy. As a result, Anna Freud viewed the play of children as fundamentally different than an adult’s free association:
The play technique worked out by Mrs. Melanie Klein is certainly valuable for observing the child. Instead of taking the time and trouble to pursue it into its domestic environment we establish at one stroke the whole of its known world in the analyst’s room, and let it move about in it under the analyst’s eye but at first without his interference…
Mrs. Klein however…assumes the same status for these play-actions of the child as for the free associations of the adult patient…if the child’s play is not dominated by the same purposive attitude as the adult’s free association, there is no justification for treating it as having the same significance. (pgs. 28-29; A. Freud, 1946)
Anna Freud’s steadfast belief that children do not have the intellectual or psychological capacity for free association, in part because they simply can’t relax and lie still for an hour on the psychoanalyst’s couch, also raises questions for the use of the second most common psychoanalytic technique, dream analysis. Dream analysis depends on the patient’s ability to freely associate about the manifest content of the dream. With children, it is necessary for the psychoanalyst to connect the manifest content with the latent content, and this process will always be somewhat suspect (A. Freud, 1946). These problems lead into another controversy, the age at which psychoanalysis can occur. Whereas Klein and her colleagues believed that psychoanalysis could occur at any age, since babies are involved in play as part of their earliest activities, Anna Freud believed that some amount of speech was necessary to form an adequate therapeutic relationship with a child (so the earliest reasonable age for psychoanalysis would be around two to three years of age; A. Freud, 1946).
In her conclusion to The Psycho-Analytical Treatment of Children , Anna Freud re-emphasizes the role that the developmental processes play as a child (and their id, ego, and superego) grows. As such, a child analyst needs to be “as intimately familiar with the normal sequence of child development as he is familiar with the neurotic or psychotic disturbances of it” (A. Freud, 1946). She specifically mentions academic psychology and the tests being created by psychologists for the measurement of personality as useful in this regard. She also mentions one test as being especially useful in examining libido development and its disturbances: the Rorschach test. Still, she acknowledges that our understanding of the developmental processes of the libido and of the ego is “very incomplete.” Yet she cautions psychoanalytic investigators “not to confine examinations to short-cuts of any kind…” (A. Freud, 1946). Clearly her concern for children, and for a professional approach to psychoanalytic research and practice, were foremost in her mind.
So what does current research tell us about the effectiveness of psychoanalysis on children? As is often the case, the results are not clear. Although a number of studies have shown that children benefit from psychoanalysis, the degree of that benefit has been disappointing (see Jarvis, 2004). When children of different age groups were studied, the results showed that psychoanalysis was more effective for younger children than it was for adolescents, something that Anna Freud would probably not have predicted. An important problem in many of the studies providing positive results, however, is that the results are based on reports by the therapists. Such reports are highly subjective and open to bias (Jarvis, 2004). Also, as we might expect, the effectiveness of psychoanalysis is dependent on the experience and skill of the analyst. Typically, analysts who have experience teaching and supervising psychoanalysis, as well as those who are prepared to try a variety of psychoanalytic techniques, achieve significantly better outcomes with their patients (Kernberg, 2004). So we must consider the question of the effectiveness of child psychoanalysis as one that remains unanswered.
Discussion Question: Is a child at play engaging in the same mental activity as an adult engaged in free association? Melanie Klein believed yes, but Anna Freud disagreed. Do you think that children are capable of the same participatory role in psychoanalysis as adults, and is play the best way to observe children?
Late in her life and career, Anna Freud extended her work beyond the psychoanalytic treatment of children to larger issues of child advocacy. In collaboration with Joseph Goldstein, a professor of law at Yale University, and Albert Solnit, a professor of pediatrics and psychiatry at Yale’s medical school and Director of the Child Study Center at Yale, she co-authored two books: Beyond the Best Interests of the Child (Goldstein, A. Freud, & Solnit, 1973) and Before the Best Interests of the Child (Goldstein, A. Freud, & Solnit, 1979). These books focus on the importance of placing the interests of children first when the government intervenes in cases involving the custody and placement of children. These situations arise is many circumstances, such as in the case of orphans or following a difficult divorce, but also in more extreme cases of abuse or when certain parents do not believe in allowing medical care for very sick children. Since these situations can pit one parent against another, or the parents against the interests of society, the authors addressed very clearly reasons why the interests of the child should be placed first:
Some will assert that the views presented in this volume are so child-oriented as to neglect the needs and rights of the adults. In fact, this is not the case. There is nothing one-sided about our position, that the child’s interests should be the paramount consideration once, but not before, a child’s placement becomes the subject of official controversy. Its other side is that the law, to accord with the continuity guideline, must safeguard the rights of any adults, serving as parents, to raise their children as they see fit, free of intervention by the state, and free of law-aided and law-abetted harassment by disappointed adult claimants. To say that a child’s ongoing relationship with a specific adult, the psychological parent, must not be interrupted, is also to say that this adult’s rights are protected against intrusion by the state on behalf of other adults.
As set out in this volume, then, a child’s placement should rest entirely on consideration for the child’s own inner situation and developmental needs… (Goldstein, A. Freud, & Solnit, 1973)
So long as the child is part of a viable family, his own interests are merged with those of the other members. Only after the family fails in its function should the child’s interests become a matter for state intrusion. (Goldstein, A. Freud, & Solnit, 1979)


Photosynthetic lineages can be found across the phylogenetic tree of protists. Most of the groups are unrelated to each other, as each major lineage acquired its chloroplast (and therefore the ability to photosynthesize) from different endosymbiotic events. For example, red and green algae belong to the same lineage (Archaeplastida). A red algal ancestor engulfed a cyanobacterial ancestor, leading to the first chloroplasts. These were inherited
vertically
--through reproduction and over evolutionary time--by the lineages of green algae. However, brown algae and diatoms inherited their chloroplasts from a secondary endosymbiotic event where their heterotrophic ancestor (something like an oomycete) engulfed a red alga. This is a
horizontal
transmission of chloroplasts between lineages, where genes (and here an organelle!) move between organisms through the environment, not through reproduction.
Endosymbiosis
The horizontal transmission of chloroplasts between lineages via endosymbiosis resulted in several unrelated groups of photosynthetic protists. The lineages covered in this section are:


4.2: Foundations of Modern Cell Theory
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Learning Objectives
- Explain the key points of cell theory and the individual contributions of Hooke, Schleiden, Schwann, Remak, and Virchow
- Explain the key points of endosymbiotic theory and cite the evidence that supports this concept
- Explain the contributions of Semmelweis, Snow, Pasteur, Lister, and Koch to the development of germ theory
While some scientists were arguing over the theory of spontaneous generation, other scientists were making discoveries leading to a better understanding of what we now call the cell theory. Modern cell theory has two basic tenets:
- All cells only come from other cells (the principle of biogenesis).
- Cells are the fundamental units of organisms.
Today, these tenets are fundamental to our understanding of life on earth. However, modern cell theory grew out of the collective work of many scientists.
The Origins of Cell Theory
The English scientist Robert Hooke first used the term “cells” in 1665 to describe the small chambers within cork that he observed under a microscope of his own design. To Hooke, thin sections of cork resembled “Honey-comb,” or “small Boxes or Bladders of Air.” He noted that each “Cavern, Bubble, or Cell” was distinct from the others (Figure \(\PageIndex{1}\)). At the time, Hooke was not aware that the cork cells were long dead and, therefore, lacked the internal structures found within living cells.
Despite Hooke’s early description of cells, their significance as the fundamental unit of life was not yet recognized. Nearly 200 years later, in 1838, Matthias Schleiden (1804–1881), a German botanist who made extensive microscopic observations of plant tissues, described them as being composed of cells. Visualizing plant cells was relatively easy because plant cells are clearly separated by their thick cell walls. Schleiden believed that cells formed through crystallization, rather than cell division.
Theodor Schwann (1810–1882), a noted German physiologist, made similar microscopic observations of animal tissue. In 1839, after a conversation with Schleiden, Schwann realized that similarities existed between plant and animal tissues. This laid the foundation for the idea that cells are the fundamental components of plants and animals.
In the 1850s, two Polish scientists living in Germany pushed this idea further, culminating in what we recognize today as the modern cell theory. In 1852, Robert Remak (1815–1865), a prominent neurologist and embryologist, published convincing evidence that cells are derived from other cells as a result of cell division. However, this idea was questioned by many in the scientific community. Three years later, Rudolf Virchow (1821–1902), a well-respected pathologist, published an editorial essay entitled “Cellular Pathology,” which popularized the concept of cell theory using the Latin phrase omnis cellula a cellula (“all cells arise from cells”), which is essentially the second tenet of modern cell theory. 1 Given the similarity of Virchow’s work to Remak’s, there is some controversy as to which scientist should receive credit for articulating cell theory. See the following Eye on Ethics feature for more about this controversy.
Science and Plagiarism
Rudolf Virchow, a prominent, Polish-born, German scientist, is often remembered as the “Father of Pathology.” Well known for innovative approaches, he was one of the first to determine the causes of various diseases by examining their effects on tissues and organs. He was also among the first to use animals in his research and, as a result of his work, he was the first to name numerous diseases and created many other medical terms. Over the course of his career, he published more than 2,000 papers and headed various important medical facilities, including the Charité – Universitätsmedizin Berlin, a prominent Berlin hospital and medical school. But he is, perhaps, best remembered for his 1855 editorial essay titled “Cellular Pathology,” published in Archiv für Pathologische Anatomie und Physiologie , a journal that Virchow himself cofounded and still exists today.
Despite his significant scientific legacy, there is some controversy regarding this essay, in which Virchow proposed the central tenet of modern cell theory—that all cells arise from other cells. Robert Remak, a former colleague who worked in the same laboratory as Virchow at the University of Berlin, had published the same idea 3 years before. Though it appears Virchow was familiar with Remak’s work, he neglected to credit Remak’s ideas in his essay. When Remak wrote a letter to Virchow pointing out similarities between Virchow’s ideas and his own, Virchow was dismissive. In 1858, in the preface to one of his books, Virchow wrote that his 1855 publication was just an editorial piece, not a scientific paper, and thus there was no need to cite Remak’s work.
By today’s standards, Virchow’s editorial piece would certainly be considered an act of plagiarism, since he presented Remak’s ideas as his own. However, in the 19 th century, standards for academic integrity were much less clear. Virchow’s strong reputation, coupled with the fact that Remak was a Jew in a somewhat anti-Semitic political climate, shielded him from any significant repercussions. Today, the process of peer review and the ease of access to the scientific literature help discourage plagiarism. Although scientists are still motivated to publish original ideas that advance scientific knowledge, those who would consider plagiarizing are well aware of the serious consequences.
In academia, plagiarism represents the theft of both individual thought and research—an offense that can destroy reputations and end careers. 2 3 4 5
Exercise \(\PageIndex{1}\)
- What are the key points of the cell theory?
- What contributions did Rudolf Virchow and Robert Remak make to the development of the cell theory?
Endosymbiotic Theory
As scientists were making progress toward understanding the role of cells in plant and animal tissues, others were examining the structures within the cells themselves. In 1831, Scottish botanist Robert Brown (1773–1858) was the first to describe observations of nuclei, which he observed in plant cells. Then, in the early 1880s, German botanist Andreas Schimper (1856–1901) was the first to describe the chloroplasts of plant cells, identifying their role in starch formation during photosynthesis and noting that they divided independent of the nucleus.
Based upon the chloroplasts’ ability to reproduce independently, Russian botanist Konstantin Mereschkowski (1855–1921) suggested in 1905 that chloroplasts may have originated from ancestral photosynthetic bacteria living symbiotically inside a eukaryotic cell. He proposed a similar origin for the nucleus of plant cells. This was the first articulation of the endosymbiotic hypothesis, and would explain how eukaryotic cells evolved from ancestral bacteria.
Mereschkowski’s endosymbiotic hypothesis was furthered by American anatomist Ivan Wallin (1883–1969), who began to experimentally examine the similarities between mitochondria, chloroplasts, and bacteria—in other words, to put the endosymbiotic hypothesis to the test using objective investigation. Wallin published a series of papers in the 1920s supporting the endosymbiotic hypothesis, including a 1926 publication co-authored with Mereschkowski. Wallin claimed he could culture mitochondria outside of their eukaryotic host cells. Many scientists dismissed his cultures of mitochondria as resulting from bacterial contamination. Modern genome sequencing work supports the dissenting scientists by showing that much of the genome of mitochondria had been transferred to the host cell’s nucleus, preventing the mitochondria from being able to live on their own. 6 7
Wallin’s ideas regarding the endosymbiotic hypothesis were largely ignored for the next 50 years because scientists were unaware that these organelles contained their own DNA. However, with the discovery of mitochondrial and chloroplast DNA in the 1960s, the endosymbiotic hypothesis was resurrected. Lynn Margulis (1938–2011), an American geneticist, published her ideas regarding the endosymbiotic hypothesis of the origins of mitochondria and chloroplasts in 1967. 8 In the decade leading up to her publication, advances in microscopy had allowed scientists to differentiate prokaryotic cells from eukaryotic cells. In her publication, Margulis reviewed the literature and argued that the eukaryotic organelles such as mitochondria and chloroplasts are of prokaryotic origin. She presented a growing body of microscopic, genetic, molecular biology, fossil, and geological data to support her claims.
Again, this hypothesis was not initially popular, but mounting genetic evidence due to the advent of DNA sequencing supported the endosymbiotic theory, which is now defined as the theory that mitochondria and chloroplasts arose as a result of prokaryotic cells establishing a symbiotic relationship within a eukaryotic host (Figure \(\PageIndex{3}\)). With Margulis’ initial endosymbiotic theory gaining wide acceptance, she expanded on the theory in her 1981 book Symbiosis in Cell Evolution . In it, she explains how endosymbiosis is a major driving factor in the evolution of organisms. More recent genetic sequencing and phylogenetic analysis show that mitochondrial DNA and chloroplast DNA are highly related to their bacterial counterparts, both in DNA sequence and chromosome structure. However, mitochondrial DNA and chloroplast DNA are reduced compared with nuclear DNA because many of the genes have moved from the organelles into the host cell’s nucleus. Additionally, mitochondrial and chloroplast ribosomes are structurally similar to bacterial ribosomes, rather than to the eukaryotic ribosomes of their hosts. Last, the binary fission of these organelles strongly resembles the binary fission of bacteria, as compared with mitosis performed by eukaryotic cells. Since Margulis’ original proposal, scientists have observed several examples of bacterial endosymbionts in modern-day eukaryotic cells. Examples include the endosymbiotic bacteria found within the guts of certain insects, such as cockroaches, 9 and photosynthetic bacteria-like organelles found in protists. 10
Exercise \(\PageIndex{2}\)
- What does the modern endosymbiotic theory state?
- What evidence supports the endosymbiotic theory?
The Germ Theory of Disease
Prior to the discovery of microbes during the 17 th century, other theories circulated about the origins of disease. For example, the ancient Greeks proposed the miasma theory, which held that disease originated from particles emanating from decomposing matter, such as that in sewage or cesspits. Such particles infected humans in close proximity to the rotting material. Diseases including the Black Death, which ravaged Europe’s population during the Middle Ages, were thought to have originated in this way.
In 1546, Italian physician Girolamo Fracastoro proposed, in his essay De Contagione et Contagiosis Morbis , that seed-like spores may be transferred between individuals through direct contact, exposure to contaminated clothing, or through the air. We now recognize Fracastoro as an early proponent of the germ theory of disease, which states that diseases may result from microbial infection. However, in the 16th century, Fracastoro’s ideas were not widely accepted and would be largely forgotten until the 19th century.
In 1847, Hungarian obstetrician Ignaz Semmelweis (Figure \(\PageIndex{4}\)) observed that mothers who gave birth in hospital wards staffed by physicians and medical students were more likely to suffer and die from puerperal fever after childbirth (10%–20% mortality rate) than were mothers in wards staffed by midwives (1% mortality rate). Semmelweis observed medical students performing autopsies and then subsequently carrying out vaginal examinations on living patients without washing their hands in between. He suspected that the students carried disease from the autopsies to the patients they examined. His suspicions were supported by the untimely death of a friend, a physician who contracted a fatal wound infection after a postmortem examination of a woman who had died of a puerperal infection. The dead physician’s wound had been caused by a scalpel used during the examination, and his subsequent illness and death closely paralleled that of the dead patient.
Although Semmelweis did not know the true cause of puerperal fever, he proposed that physicians were somehow transferring the causative agent to their patients. He suggested that the number of puerperal fever cases could be reduced if physicians and medical students simply washed their hands with chlorinated lime water before and after examining every patient. When this practice was implemented, the maternal mortality rate in mothers cared for by physicians dropped to the same 1% mortality rate observed among mothers cared for by midwives. This demonstrated that handwashing was a very effective method for preventing disease transmission. Despite this great success, many discounted Semmelweis’s work at the time, and physicians were slow to adopt the simple procedure of handwashing to prevent infections in their patients because it contradicted established norms for that time period.
Around the same time Semmelweis was promoting handwashing, in 1848, British physician John Snow conducted studies to track the source of cholera outbreaks in London. By tracing the outbreaks to two specific water sources, both of which were contaminated by sewage, Snow ultimately demonstrated that cholera bacteria were transmitted via drinking water. Snow’s work is influential in that it represents the first known epidemiological study, and it resulted in the first known public health response to an epidemic. The work of both Semmelweis and Snow clearly refuted the prevailing miasma theory of the day, showing that disease is not only transmitted through the air but also through contaminated items.
Although the work of Semmelweis and Snow successfully showed the role of sanitation in preventing infectious disease, the cause of disease was not fully understood. The subsequent work of Louis Pasteur, Robert Koch, and Joseph Listerwould further substantiate the germ theory of disease.
While studying the causes of beer and wine spoilage in 1856, Pasteur discovered properties of fermentation by microorganisms. He had demonstrated with his swan-neck flask experiments (link) that airborne microbes, not spontaneous generation, were the cause of food spoilage, and he suggested that if microbes were responsible for food spoilage and fermentation, they could also be responsible for causing infection. This was the foundation for the germ theory of disease.
Meanwhile, British surgeon Joseph Lister (Figure \(\PageIndex{5}\)) was trying to determine the causes of postsurgical infections. Many physicians did not give credence to the idea that microbes on their hands, on their clothes, or in the air could infect patients’ surgical wounds, despite the fact that 50% of surgical patients, on average, were dying of postsurgical infections. 11 Lister, however, was familiar with the work of Semmelweis and Pasteur; therefore, he insisted on handwashing and extreme cleanliness during surgery. In 1867, to further decrease the incidence of postsurgical wound infections, Lister began using carbolic acid (phenol) spray disinfectant/antiseptic during surgery. His extremely successful efforts to reduce postsurgical infection caused his techniques to become a standard medical practice.
A few years later, Robert Koch (Figure \(\PageIndex{5}\)) proposed a series of postulates (Koch’s postulates) based on the idea that the cause of a specific disease could be attributed to a specific microbe. Using these postulates, Koch and his colleagues were able to definitively identify the causative pathogens of specific diseases, including anthrax, tuberculosis, and cholera. Koch’s “one microbe, one disease” concept was the culmination of the 19th century’s paradigm shift away from miasma theory and toward the germ theory of disease. Koch’s postulates are discussed more thoroughly in How Pathogens Cause Disease .
Exercise \(\PageIndex{3}\)
- Compare and contrast the miasma theory of disease with the germ theory of disease.
- How did Joseph Lister’s work contribute to the debate between the miasma theory and germ theory and how did this increase the success of medical procedures?
Clinical Focus: Part 2
After suffering a fever, congestion, cough, and increasing aches and pains for several days, Barbara suspects that she has a case of the flu. She decides to visit the health center at her university. The PA tells Barbara that her symptoms could be due to a range of diseases, such as influenza, bronchitis, pneumonia, or tuberculosis.
During her physical examination, the PA notes that Barbara’s heart rate is slightly elevated. Using a pulse oximeter, a small device that clips on her finger, he finds that Barbara has hypoxemia—a lower-than-normal level of oxygen in the blood. Using a stethoscope, the PA listens for abnormal sounds made by Barbara’s heart, lungs, and digestive system. As Barbara breathes, the PA hears a crackling sound and notes a slight shortness of breath. He collects a sputum sample, noting the greenish color of the mucus, and orders a chest radiograph, which shows a “shadow” in the left lung. All of these signs are suggestive of pneumonia, a condition in which the lungs fill with mucus (Figure \(\PageIndex{6}\)).
Exercise \(\PageIndex{4}\)
What kinds of infectious agents are known to cause pneumonia?
Key Concepts and Summary
- Although cells were first observed in the 1660s by Robert Hooke, cell theory was not well accepted for another 200 years. The work of scientists such as Schleiden, Schwann, Remak, and Virchow contributed to its acceptance.
- Endosymbiotic theory states that mitochondria and chloroplasts, organelles found in many types of organisms, have their origins in bacteria. Significant structural and genetic information support this theory.
- The miasma theory of disease was widely accepted until the 19th century, when it was replaced by the germ theory of disease thanks to the work of Semmelweis, Snow, Pasteur, Lister, and Koch, and others.
Footnotes
- 1 M. Schultz. “Rudolph Virchow.” Emerging Infectious Diseases 14 no. 9 (2008):1480–1481.
- 2 B. Kisch. “Forgotten Leaders in Modern Medicine, Valentin, Gouby, Remak, Auerbach.” Transactions of the American Philosophical Society 44 (1954):139–317.
- 3 H. Harris. The Birth of the Cell . New Haven, CT: Yale University Press, 2000:133.
- 4 C. Webster (ed.). Biology, Medicine and Society 1840-1940 . Cambridge, UK; Cambridge University Press, 1981:118–119.
- 5 C. Zuchora-Walske. Key Discoveries in Life Science . Minneapolis, MN: Lerner Publishing, 2015:12–13.
- 6 T. Embley, W. Martin. “Eukaryotic Evolution, Changes, and Challenges.” Nature Vol. 440 (2006):623–630.
- 7 O.G. Berg, C.G. Kurland. “Why Mitochondrial Genes Are Most Often Found in Nuclei.” Molecular Biology and Evolution 17 no. 6 (2000):951–961.
- 8 L. Sagan. “On the Origin of Mitosing Cells.” Journal of Theoretical Biology 14 no. 3 (1967):225–274.
- 9 A.E. Douglas. “The Microbial Dimension in Insect Nutritional Ecology.” Functional Ecology 23 (2009):38–47.
- 10 J.M. Jaynes, L.P. Vernon. “The Cyanelle of Cyanophora paradoxa : Almost a Cyanobacterial Chloroplast.” Trends in Biochemical Sciences 7 no. 1 (1982):22–24.
- 11 Alexander, J. Wesley. “The Contributions of Infection Control to a Century of Progress” Annals of Surgery 201:423-428, 1985.


8.2: Infection Introduction
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Have you ever wondered how nurses can be exposed to patients with communicable diseases day after day and not become ill? There are many factors that affect the body’s ability to defend against infection and place some individuals at greater risk of developing an infection. When an infection does occur, early recognition is important to prevent it from spreading within the individual, as well as to others. Protecting people from developing an infection, as well as preventing the spread of infection, is a major concern for nurses. This chapter will discuss the physiology of the inflammation and infectious processes and nursing interventions to prevent the spread of infection.


14.2: Non-Profit Organizations
Learning Outcomes
- Evaluate a non-profit organization’s performance using financial and non-financial data
Since non-profit accounting systems are beyond the scope of this course, we will briefly discuss financial and non-financial performance goals.
Non-profit organizations may have different goals and needs than for-profit organizations as they work towards a mission or goal that is not profit driven. Financial aspects will include meeting budgets and following granting and funding organization’s reporting requirements. This process too, will vary by organization.
Non-financial goals are many in non-profits. Serving a specified number of clients is typically a very important goal in most agencies. Agencies also need “inkind” or non financial support through volunteer hours and donated supplies. Many agencies have requirements through funders, to obtain a certain amount of match to meet goals. Let’s look briefly at a small non-profit organization that operates a food shelf and retail thrift store.
| Budget | Actual | Over/(under) budget | % Over/(under) budget | |
|---|---|---|---|---|
| Income | ||||
| Retail Sales | $5,000 | $6,120 | $1,120 | 22% |
| Donations | $1,250 | $286 | ($424) | −34% |
| Grants | $1,250 | $1,250 | $0 | 0% |
| Total Income | $7,500 | $8,196 | $696 | |
| Expenses | ||||
| Rent | $500 | $500 | 0 | 0 |
| Utilities | $225 | $280 | $55 | 24 |
| Payroll | $5,000 | $5,125 | $125 | 3 |
| Supplies | $500 | $700 | $200 | 40 |
| Marketing | $500 | $400 | ($100) | −20% |
| Fundraising | $500 | $250 | ($250) | −50 |
| Total Expenses | $7,225 | $7,225 | $30 | 0 |
| Net Position | $275 | $941 | $666 | 242 |
So what would some issues be that this little agency would need to look at from a financial standpoint? The first thing that stands out is a pretty large difference in donation levels compared to what was budgeted. This leads to a potential non-financial issue as well. We could then evaluate how donations are being requested. Are there a certain number of phone calls to be made each month by volunteers? Is the clerk at the retail store asking for donations at the conclusion of a sale?
Payroll was a bit high, so evaluating that expense line from a financial perspective would include looking at the hours worked to determine if overtime was a factor. Non-financial aspects might include analyzing the time used for opening and closing the store, or looking at procedures that may help to reduce hours worked.
As you can see, the non-profit organization brings a whole different set of challenges that are not within the scope of this course. This agency is not interested in making a profit, but in meeting the goals of the organization, by providing food to families in need through the sale of donated items. It is a mission driven organization rather than profit driven!
Practice Questions


7: Mathematics and the Arts
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- 7.1: Projective Geometry
- Before drawing a 3-dimensional object on a flat surface, such as a sketch book or a canvas, one needs to learn some principles of perspective. This skill, based on projective geometry and developed during the Renaissance, allows the artist to draw things more realistically. All of us have seen, for instance, pictures of railroad tracks and straight highways where the two lines, though parallel in space, appear to converge to a point, referred to as the principal vanishing point.
-
- 7.2: The Golden Ratio and Fibonacci Sequence
- In this section, we will discuss a very special number called the Golden Ratio. It is an irrational number, slightly bigger than 1.6, and it has (somewhat surprisingly) had huge significance in the world of science, art and music. It was also discovered that this number has an amazing connection with what is called the Fibonacci Sequence, originally studied in the context of biology centuries ago. This link among algebra, biology, and the arts suggests the mathematical unity of the world.
Thumbnail: Golden spirals are self-similar. The shape is infinitely repeated when magnified. (Public Domain; Jahobr via Wikipedia )
Contributors and Attributions
-
Saburo Matsumoto
CC-BY-4.0


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gender
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male and female characteristics that are socially constructed
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gender identity
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a person’s internal experience and belief of gender, which may or may not correspond to their physiology or designated sex at birth
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geographical disparities
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differences in health care access and outcomes based on where an individual lives
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geography
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a science that deals with the description, distribution, and interaction of the diverse physical, biological, and cultural features of the earth’s surface
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health care disparities
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differences among groups related to access and use of health care
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health disparities
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health differences linked to social, economic, and/or environmental disadvantages
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health equity
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the state in which everyone has a fair and just opportunity to attain their highest level of health
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intersectionality
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intersecting disadvantages related to the inequities, injustices, oppressions, and privileges perpetuated by structures including racism, classism, colonialism, sexism, heterosexism, ableism, and others
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minority health
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distinctive health characteristics and attributes of racial or ethnic minority populations who are socially disadvantaged due in part to being subject to racist or discriminatory acts and are underserved in health care
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sex
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the physiological and biological characteristics of males and females
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socially disadvantaged
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those who have experienced prejudice or bias because of their identities as members of racial, ethnic, or cultural groups, without regard for their individual qualities and stemming from circumstances beyond their control