Frequency of bowel movements varies widely among individuals, as well as varying widely for any single individual. In studies on the subject, approximately 50 to 70 percent of people surveyed report having a single daily bowel movement. Outliers range from one movement every three days to three movements a day.
Cell theory was eventually formulated in 1839. This is usually credited to Matthias Schleiden and Theodor Schwann. However, many other scientists like Rudolf Virchow contributed to the theory. The three tenets to the cell theory are as described below: All living organisms are composed of one or more cells.
1838 Matthias Schleiden-First to observe and report that all plants were composed of cells. 1839 Theodore Schwann-First to observe and report that all animals were composed of cells. Theodore Schwann and Schleiden are attributed to the first two points of the Cell Theory.