528 Transactions. — Miscellaneous. 



The conditions necessary to successful invasion (rest, 

 weakened tissue, &c.) are also present in the brain membranes 

 of some yoiQig and weakly students — here tubercular menin- 

 gitis arises ; or in the knees of housemaids or men used to 

 scrubbing floors — here " housemaid's knee," or " white swell- 

 ing," arises; or the glands of the neck may be the seat of in- 

 fection, or the bones of the spine, or the hip- joint, constituting 

 the conditions known generally as spinal disease and hip 

 disease respectively ; or the lungs, the intestines, or the neck- 

 glands in cattle may be affected, constituting bovine tuber- 

 culosis. In short, any part of the human body, or of the body 

 of an ox, may become invaded by the bacillus of tubercle ; and 

 the want of uniformity in the nomenclature of the disease is 

 due to the fact that the names w^ere given before the true 

 nature of the affection was understood. 



It is not necessary to make reference to the destructive 

 processes that go on after the invasion of the body-tissues by 

 the bacillus of tubercle, as the purpose of this paper is to deal 

 with the subject in its public-health aspect ; and the points of 

 importance in this connection are — (1) That tuberculosis is a 

 germ disease ; (2) that it exists in man and in some of the 

 animals he uses for food ; (3) that it is infectious, being com- 

 municable from man to man and animal to man ; (4) that, 

 being infectious, it is preventible ; (5) and, being preventible, 

 it comes within the province of State medicine. 



First, then, tuberculosis is infectious ; but the infection is 

 not virulent, the vitality of the bacillus is low, and the condi- 

 tions necessary to successful invasion are nu.merous ; while 

 the power of immunity, or resistance to infection, is an in- 

 creasing factor in healthy individuals. But, aj)art from the 

 bacterial nature of the disease, and the truth of the statement 

 that diseases of germ origin are all more or less infectious, 

 instances of direct infection are constantly under notice. 

 Individuals in the saine house are infected by each other ; 

 successive families following one another as tenants of the 

 same house have fallen victims to the disease ; and such 

 houses have been known to be infected for generations. 

 Eespired air, or air vitiated by germs from dried expectoration, 

 is the medium by which infection is conveyed in such places. 

 The air in hospitals for consumptives has been found to con- 

 tain the tubercle bacillus, and to have the power of inoculating 

 nutritive media, from which the disease has been produced 

 experimentally. 



The milk and flesh of affected cattle form another, and 

 perhaps the most important, medium by which the disease is 

 communicated to man. That these tissues contain the bacilli 

 of tuberculosis has been frequently demonstrated, and the dis- 

 ease has been produced experimentally through their agency. 



