The movement of extirpated intestine of the young rabbits, reared under the same hot and humid environment as previous two experiments for 46 days, was observed by Magnus's method. The following results were obtained 1. The movement of extirpated small intestine was reduced under these conditions, and effects of adrenalin and acetylcholin were milder than that of the control. 2. There was no difference in the movement of extirpated colon between the test and control animals. The effects of adrenalin were reduced and the effects of acetylcholin were increased under these conditions. However, in the rabbits reared in these environments for only two weeks, the movement of estirpated colon was reduced and the effects of adrenalin and acetylcholin showed an increase as compared with that of control animals. These results indicate that in high temperature and high humidity some disharmony is caused to the autonomic nervous system of young animals and the function of their digestive organs is disturbed. Generally, during the early summer in Japan, when it is very hot and humid it can be said that the function of digestive organs of Japanese infants who are usually heavily clothed are apt to be decreased. Therefore, it can be considered that such disturbances of digestive function during the sultry season play a important part in causing attacks of "Jusho-Shokafuryosho", a serious infantile summer dyspepsia in Japan.