11 



l)egan to show siuiihu' symptoms, and in fonr months after the first 

 one was seized by the disease, there were nine cases of consumption 

 in the Convent, some of them among those who were formerly 

 thought to be exceptionally healthy. Fonr of the inmates died of the 

 disease, and the others were lingering along with the chronic form. 

 The director of the Convent then took energetic measures to isolate 

 the sick and send away the ailing and the epidemic was stopped. 



IS BOVINE TUBERCULOSIS CONTAGIOUS? 



Veterinary surgeons have for a long time insisted that bovine tuber- 

 culosis is contagious, and the veterinary journals are teeming with 

 cases pointing unmistakably to its contagious character. 



The experiments of Villemin, Cohnlieim, Toussaint, Koch and 

 others leave no possible doubt of the contagiousness of the disease. 

 Dr. Koch inoculated the tuberculous matter from diseased animals 

 into healthy ones, and reproduced the disease in every case. 



To prove that it was the parasite itself that caused the disease and 

 not some virus in which it was imbedded in the diseased tissue, Koch 

 cultivated his bacilli artificially for a long time, and through many 

 successive generations, by a very ingenious and novel method. Be- 

 fore this time, bacteria had been cultivated on slices of potato, 

 beet, etc., or in liquid substances, as beef tea. It is a well known 

 fact as stated by Tyudall, that there are many species of bacteria 

 differing from one another in the effects which they produce in the 

 medium in which they are cultivated. Like other plants, they "ex- 

 haust the soil " as it were. It is also known that bacteria are so 

 universally distributed that the examination of any natural medium 

 attacked by them is almost sure to yield evidence of the presence of 

 more than one species, the various species being grouped together in 

 inextricable confusion. On this account it has been extremely diffi- 

 cult to determine what effects are due to one species of bacterium 

 and what to another. It has often been impossible to determine in 

 such a mixture of forms, one species from another. 



Dr. Koch cultivated the Bacillus of tuberculosis on a thin layer of 

 blood-serum spread on a glass microscope slide. This blood-serum was 

 prepared by allowing fresh blood to remain in a vessel until it had 

 clotted, and the clot had separated from the serum. This serum was 

 then put into test-tubes and closed with a plug of cotton to exclude 

 all germs floating in the air. It was then exposed to a temperature 



