Four dogs having permanent gastric fistulae of the "valve" type were fed artificial diets adequate except in vitamin B. At intervals the motility of the empty stomach was recorded (Carlson technic). In mild cases of vitamin B deficiency, evidenced by an anorexia, there is little if any change in the character of the gastric contractions, but in severe cases, characterized by nervous and muscular symptoms as well as by anorexia, there is gastric atony. Successful vitamin B therapy applied to such cases is associated with rapid improvement in tone of stomach musculature. Furthermore, continued feeding of liberal quantities of vitamin B to an organism subsisting on a diet adequate in other respects aids in maintaining a satisfactory gastric tonicity.