many of tlic most coinpeteut observers among its advocates. Ac- 

 cording to this theory, tuberculosis is a specific infectious disease, 

 caused by a particular poison called "tubercular virus," which is 

 formed in cheesy matter of every description. If this virus be ab- 

 sorbed into the blood, it can generate miliary tubercles in all predis- 

 posed organs. 



Previous to this time, various experiments had been made by intro- 

 ducing tuberculous matter into the lower animals for the purpose of 

 determining whether they could be infected with the disease ; and 

 these experiments proved so successful that, in 1864, Villemin ex- 

 pressed the belief that tuberculosis is a specific infectious disease, 

 independent of other internal and external circumstances, and can 

 only be caused by the introduction of tuberculous matter into the 

 body, and that it can be transferred from animal to animal, or from 

 man to animal by vaccination. It is seldom that so startling an 

 assertion has given greater impulse to scientific labors in the field of 

 experimental pathology than this doctrine of Villemin. The most 

 prominent men of science exerted their utmost powers to prove or dis- 

 prove the new doctrine. The experiments made with tuberculous 

 matter for the purpose of infecting other animals were by inoculation, 

 inhalation or by feeding. 



Innumerable experiments of almost every form and variety were 

 made by inoculation. Tuberculous material from men and the lower 

 animals was introduced under the skin, into the abdominal cavity, 

 the larger blood-vessels, the anterior chamber of the eye, and even 

 into the lungs themselves. 



Toussaint concluded from the experiments which he made that no 

 disease is more infectious than tuberculosis, and that all the fluids of 

 the body, the blood, nasal secretion, saliva, the juices of the tissues, 

 the urine, and even the lymph from the vesicles of the inoculated 

 variola (vaccine matter) are all able to convey the infectious material 

 of tuberculosis. These experiments were made upon cows, calves, 

 goats, swine, rabbits and dogs, and almost invariably led to the de- 

 velopment of miliary tuberculosis. 



Ziirn, in 1871, observed micrococci in the blood of a cow that had 

 died of tuberculosis, and Chauveau made similar observations in the 

 following year, and the opinion prevailed to some extent that the mi- 

 crococcus was the real cause of this disease. 



On the 24111 of March, 1882, Dr. Koch read a paper before the 

 Physiological Society of Berlin, which was as remarkable as it was 



