When experimental surgery on the dog became general, it was soon discovered that occasional infections occurred. Postoperative infections were not new to the veterinary surgeon, but his technic was crude, and he considered most infections the result of wound contamination. In experimental procedures, even when aseptic technic was employed, infection resulted in certain experimental work having to do with obstruction of the small intestine if circulation was inhibited. Bacterial analysis of these wound infections yielded a high percentage of organisms from the Clostridium group. There was much speculation at that time on the manner in which these organisms gained entrance to the body. Early investigators were of the opinion that the animals were eating contaminated food, and the organisms present in the lumen of the bowel found ready accessability to the region where the experimental surgery was performed.