ABSTRACT
This subject must be discussed, as it has filled a very considerable place in the history of public health and in my personal epidemiological work in the last half-century. From 1912 onwards there has been a marvellous reduction in the toll levied by diarrhœa on infantile life, a change which is almost as striking as the reduction of typhoid fever. The reduction in the prevalence of diarrhœa lagged behind that of typhoid, suggesting at once in retrospect a difference in the causation of the two diseases.
