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.
Through their studies they concluded that all living things were made up of cells and that a cell is the smallest unit of organization in a living thing. These ideas formed the basis for cell theory. In 1858, Rudolf Virchow studied cellular pathology and proposed that all cells come from other cells.