Abstract
In the cows' intestine there is no isotony with the blood serum. In the upper part of the small intestine the chyme is strongly hypertonic but as it passes along the intestinal tract to the large intestine it becomes more and more hypotonic. The hypertony in the small intestine is not due to inorganic elements but is caused by organic non-electrolytes.In the large intestine hypotony is the result of strong selective absorption of sodium against a concentration gradient.This is an important aspect of the sodium metabolism of the cow. Chlorine is also absorbed from the large intestine against a concentration gradient.