TUBERCULOSIS 147 
and syphilis and declared the flesh of affected animals to be fit for 
food. This led finally to the changing of all laws throughout Prussia 
against the use for food of flesh from animals affected with the 
disease. Tscheulin, in 1816, recognized in reference to the infection 
of meat three degrees of bovine tuberculosis, viz.: (1), in which the 
tubercles were to be removed; (2), in which the diseased parts were 
to be destroyed and the meat sold at a low price; and (3), those cases 
in which the lesions were so extensive that the whole carcass must be 
rejected. 
The study of the lesions themselves gave rise to a number of beliefs 
concerning their nature. Thus, Virchow, Schippel and others 
declared that the tubercles in cattle were lympho-sarcomata. Leiser- 
ing considered them simply as sarcomata. Spinola and Haubner 
maintained that human and bovine tuberculosis were identical. 
In 1865, Villemin showed that tuberculosis was due to a specific 
infection. He produced the disease in rabbits by inoculating them 
with tuberculous material from human subjects. He also produced 
the disease by feeding experimental animals and by causing them to 
inhale tuberculous material. Chauveau, in the same year, produced 
the disease in cows. These results were soon confirmed by Klebs, 
Cohnheim and Gerlach. These experiments, in which the disease 
was produced in one species with tuberculous material from another, 
followed by the discovery by Koch of the specific bacterium of the 
disease, led to the view that tuberculosis in all species of mammals 
was identical. This generally accepted belief caused sanitarians to 
look upon tuberculosis in cattle as a great menace to public health. 
The result was that during the closing decade of the last century 
this disease in cattle was treated more vigorously as a menace to the 
human species than as a destructive disease of animals. 
In 1896, Dr. Theobald Smith pointed out that for certain animals 
the tubercle bacteria from cattle were more virulent than those from 
man and further that there were certain morphological and cultural 
differences existing between them. In 1898, he published the results 
-of a more extended series of investigations. Since that time a number 
of investigators have arrived at the same conclusion. The fact has 
come to be well known that certain differences exist between the 
bacteria of tuberculosis found in the human and in the bovine species. 
Koch’s experiments reported at the tuberculosis congress in London 
in July, 1901, give additional evidence of a difference in virulence 
for experimental animals of the bacteria of human and of bovine 
