Of the 300 stomach specimens resected at the FukudaSurgery of Tokyo University since Sept., 1947, 197 cases of gastric cancer were found, and from these the very earliest gastric cancer specimens were selected for the histological study of the development and growth of gastric cancer(10). In 2 of these it seemed that the form of development of gastric cancer was shown in the most convenient way. Of course, in both of these cases the histologic picture was what should be called carcinoma in situ(8).In regard to the development of carcinoma in situ, Konjetzny(5,6)stated that the mother body is a diffuse atrophic or atrophic‐hyperplastic gastritis while Bertrand(4)explained that it is due to “Degenerescence in situ,” developing in localized specific gastritis. Ewing(2)is also trying to recognize the development from a special cancerigenic atrophic‐hyperplastic gastritis as a mode of development of gatric cancer.For the purpose of analyzing more clearly and also stereoscopically the relation between carcinoma in situ focus selected in the way mentioned above and the surrounding part of the focus, the author made serial sections and was able to come to a certain conclusion.At first, the author is going to describe thes