Abstract
The fresh weight of the rat's small intestine together with its contents, as well as the intestinal tissue alone, was doubled during the 15 days following infestation by the nematode N. muris (Yokogawa, 1920). This increase, which was independent of the growth of the rat, was largely due to a two-fold increase in the water content of both the lumen and the tissues. The dry weight of the tissues was increased by half.