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.
He observed living cells; called some of them 'animalcules.' Some of the small 'animalcules' are now called bacteria, which are single-cell organisms. Matthias Schleiden (1838) was a German botanist who viewed plant parts under a microscope and discovered that plant parts are made of cells. Theodor Schwann (1839) was a German zoologist who viewed animal parts under a microscope and discovered that animal parts are also made of cells.