According to my researches into this subject this problem will not be successfully solved by the efforts now being made to secure the use of sterilized milk. I am, in fact, in doubt whether milk sterilization as at present practised can much longer pass as a hygienic measure. For the present, to be sure, we have nothing better. But the discussion of this question does not fall within the scope of this lecture. I have quoted the statistics of the high infant mortality in our large cities merely in order to advance a further epidemiological argument for my assertion that the infant alimentary tract is defenseless against infectious agents whether these are living or not. Even the infectious toxins pass unchanged through the intestinal mucous membrane of very young individuals, though not through that of healthy older ones. A real advance in milk hygiene can, however, be begun even now if the milk be pasteurized at the dairies and not at the large receiving-stations in the cities. In the raising of calves, this procedure has proven of great value. I have made exhaustive studies to discover why the intestinal mucous membrane of the young should offer so little resistance to the passage of corpuscular infectious substances. I shall content myself here with the statement that the mucous membrane of new-born individuals possesses no continuous epithelial covering and that the gland-tubes of the ferment-producing glands are little, if at all, developed at this time. By having thus presented to you the results of my experiments and explained my epidemiological views, I have not really deviated from the subject of the suppression of tuberculosis. We have seen that the tubercle bacilli which gain access to the system through the alimentary tract in infancy constitute the important etiological factor in the production of the tubercular infection which leads to consumption, and I believe that the realization of this great fact will supply us with a rational plan for combating tuberculosis. It will be necessary to strive more than ever to secure a suitable milk diet for new-born and very young children, one based on sound experimental investigations. The as yet unsolved problem, that of a rational milk hygiene in the suppression of tuberculosis, coincides with the problem of milk-feeding of infants in general. The mode of infection is everywhere the same, but the infectious agents are of great variety. Most of them excite acute diseases which end either fatally or in entire recovery; in the latter case with a simultaneous development of immunity. The virus of tuberculosis, however, behaves quite differently, creeping in most insidiously, all unnoticed, and being in this respect analogous only to the virus of leprosy, of syphilis, or possibly of malaria in tropical countries. It may be months, years, or decades before the infection leads to manifest disease. This depends on the virulence of the virus,