We experimented by perfusing lndia ink.Ringer's solution to the esophagus，stomach, small intestines and rectum of such animals having blood capillary vessels as the earthworm，octopus，Cyprinus auratus，carp，frog，toad，salamander，turtle，chicken，rat，rabbit，cat and man. The distributory structure of blood capillary vessels in digestive organs becomes
complicated as the animal evolves. In the earthworm，it is a blood capillary net of a
single layer，but it forms stratified blood capillary nets in the octopus. ln the Cyprinus auratus，the blood capillary nets become prominent. In mammals and man，especially in their small intestines， the blood capillary nets are very prominent. These findings represent differences of digestive and absorptive functions among the animals. The blood capillary density is remarkable in the small intestines as compared with those in the mucous membrane of the esophagus，stomach，and large intestines in all animals. It is considered that blood capillary density of these regions show the difference of their digestive and absorptive functions.