CONTAGIOUS DISESAES-NEW DISCOVERIES. 
397 
certain new facts bearing an intimate relation to the practical 
duties of our own profession, through the questions of sanitary 
medicine which they involve. 
The days of guess-work and unsnstained, though more or less 
plausible hypothesis, are gone by. . The theories of spontaneous 
growth, of the climateric influences, and the old errors of 
hygiene, have vanished in the presence of the truths which have 
become the offspring and reward of close observation and rigid 
experiment; of microscopic research, and of practical medicine, 
as tested in the labraotory. And in respect to many and the most 
important of the contagious diseases, and especially as to tubercu¬ 
losis, anthrax and rabies, it is in our power, thanks to the works 
of Koch, of Pasteur, of Chauveau, and others, not only to know 
their true nature, but also to apply, at least to the last two, 
positive prophylactic measures, the application of which lies within 
our own domain of veterinary medicine. 
Allow me then to offer a few remarks upon the new facts 
which concern these three affections. 
My first reference will be to tuberculosis, that protracted, in¬ 
sidious and fatal disease, which every year terminates so many 
human lives, and destroys, besides, so large an amount of valu¬ 
able property in its animal victims, and upon which so much has 
been written; which has been attributed to so many specific orig¬ 
inating causes; whose contagious nature has been so well demon¬ 
strated by Professor Villemin first, and subsequently by Chau¬ 
veau, Koch, Toussaint and others; and which is now well under¬ 
stood as to its cause and nature, through the invaluable researches 
of Koch and Toussaint. To whom belongs the priority of the 
discovery is a question still in doubt. In 1881 Toussaint de¬ 
scribed “ a mass of granulations ” which he had observed on the 
field of the microscope, in examining tuberculosis cultures, and 
he formed the judgment that these granulations were the agents 
of virulency. These were small inicroccocci, which presented 
themselves in the liquid, either isolated, germinated or disposed 
in varying series of five, six, ten or more. 
At a later period, however, Koch published the result of his 
observations, and in his view, these agents became a bacillus, pre- 
