CHARLES BOLDUAN. BROOKLYN, July, 1904. CONTENTS. PAGE THE SUPPRESSION OF TUBERCULOSIS (THE CASSEL LECTURE) 1 OBSERVATIONS CONCERNING PHTHISIOGENESIS IN MAN AND ANIMALS 45 SUGGESTIONS CONCERNING THE HYGIENE OF COW-STABLES AND THE PRODUCTION OF MILK FOR INFANT-FEEDING 60 SYNOPSIS OF THE METHOD OF MAKING PROTECTIVE INOCULATIONS OF CATTLE IN AGRICULTURAL PRACTICE 69 CONDITIONS CONCERNING THE DISTRIBUTION OF THE PROTECTIVE VIRUS 75 APPENDIX 81 THE SUPPRESSION OF TUBERCULOSIS. THE CASSEL LECTURE.[1] Although in this lecture I have planned to discuss mainly the suppression of human tuberculosis, my experiences with bovine tuberculosis cannot be omitted; for not only have I strong reasons for believing that bovine tuberculosis plays an important rôle in the etiology of human tuberculosis, but I am also firmly convinced that by means of the knowledge gained from the study of bovine tuberculosis, we shall be able to prevent to a great extent human tubercular consumption, and favorably influence the course of already existing tubercular diseases. Both human pulmonary consumption and _perlsucht_ of cattle (which often leads to consumption) are caused by minute vegetable organisms, which it is impossible to differentiate either microscopically or culturally,--the tubercle bacilli of Koch. It is impossible to have either tubercular pulmonary consumption or _perlsucht_ without the presence of these tubercle bacilli; and no matter how susceptible to tuberculosis an individual may be, a tubercular infection cannot take place if these bacilli be absent. In order for the disease to develop, three factors must always be present: first, the susceptible organism; second, the vegetable parasite; and third, the necessary opportunity to infect. Under the last I understand all the conditions necessary to bring the virus to such a part of the living organism as will enable it to enter either into the circulation or into other body juices. Every human individual is by nature susceptible to the action of tubercle bacilli which have entered his body juices. This is true not only of human but also of bovine tubercle bacilli. I emphasize this now but shall give my proofs later. But not every tubercular infection of the tissues leads to consumption. Frequently the tubercular infection is followed by such slight disturbances of health that it remains latent throughout an entire lifetime and is only discovered at autopsy.