The author used the following methods to investigate the multiplication of coli bacilli, which is regarded to be responsible to disturb the healing of the wound in the anastomosis in rabbit. In the intestine were used 3 portions, namely, upper oral, middle and lower aboral, and in each portion were applied end-to-end and side-to-side anastomosis respectively. After a certain day each portion was resected and cultivated the coli bacilil from the intestinal content with dilution method. Simultaneously pH and diastase values of the intestinal content were measured and the following results were obtained: 1. In the normal rabbit the intestine is nearly sterile and at least the coli bacilli are not found, but from the cecum aboral the coli bacilli and other various bacilli increase in large number. 2. In each intestinal portion there is no significant difference in the pH and diastase value. Trypsin is not certificated. 3. However, in the anastomosis applied intestine a fairly large number of the coli bacilli are observed in each portion. 4. As regards to the method of the anastomosis a tendency of larger increase of coli bacilli is recognized in the side-to-side anastomosis than in the end-to-end anastomosis. 5. It is hard to recognize a definite tendency of the multiplication of coli bacilli in the unit weight of the intestinal content. 6. As to the multiplication, the coli bacilli increase most in number in 5 to 7 days after the operation and in the lapse of 2 weeks they decrease already moderately. This fact is considered to be in a correlation to the term apt to occur the insufficiency of the anastomosis. 7. The values of pH and diastase are hardly different from the normal values and are not influenced by the ascent of coli bacilli to the upper oral portion of the intestine.