Another important problem, one regarding hereditary immunity, is already nearer solution. I believe I am warranted in saying that, as a rule, the immunity against tuberculosis is not transmitted by the cow to her calf during intra-uterine life. One can readily be deceived by cases of apparent hereditary immunity. For example, in examining the fourteen-day-old calf of a highly immunized cow, I found the calf to possess a comparatively high degree of immunity against _perlsucht_ bacilli. Without my previous experience with infantile immunity to guide me, I might easily have been led into the error of assuming this to be a case of hereditary immunity. Comparative tests, however, have made it very probable that the immunity, undoubtedly possessed by this calf, was derived from the milk of the immune cow with which the calf was nourished. It will still be some time before I can present any experimental evidence to show whether a cow, less highly immunized than the one just mentioned, also produces a milk which possesses protective immunity, and if so, how far it is possible to increase this property; whether such a milk can be used to combat human tuberculosis; and finally, whether it can be transported long distances without losing this property. I have, to be sure, every reason to hope that we are on the right track when we believe that immune milk constitutes a remedy for tuberculosis with which no other remedy can even remotely compare. You will, I am sure, believe that I shall leave nothing undone which will lead to a realization of these hopes. Right here, perhaps, it is well to say that, for the purpose of making very careful therapeutic experiments, I am delivering immune milk to only a few of my medical friends. I cannot, therefore, meet the many demands for this remedy coming from medical and other sources. They are so numerous that I cannot even answer them all. When, as a result of these clinical experiments, the conditions and restrictions are determined under which immune milk exerts its therapeutic action, I shall make public all the facts in regard to this remedy, and thus make it accessible to every one. In the mean time I believe it will serve a very useful purpose if I publish in readily comprehensible form the scientific facts on which my plans for the suppression of tuberculosis rest. With this, of course, will come a discussion of controversial points in the field of tuberculosis investigation which have attracted the attention not only of the medical profession, but also of the laity.