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.
This led to the knowledge that all living things were made of cells. In 1855, German physician Rudolph Virchow theorized that all living cells come from other living cells. The contributions of these people led to what we now refer to as the cell theory. This theory states: 1. All living things are made of one or more cells. 2. The cell is the smallest unit of a living organism. 3. Cells come from other cells.