Differences in incidence of various diseases over the course of several yrs. are noted. The number of cases of gastric ulcers treated in 3 Russian hospitals is noted from 1914-28; a sharp peak in 1921 is correlated with poor nutrition. Nutritional defects also affect the incidence of wound infections, hernia and volvulus. Several other diseases of varying incidence are also discussed. Through mutations of germ plasm, new diseases may be expected to appear.