New YorK AGRICULTURAL EXFERIMENT STATION. 29 
ACKNOWLEDGMENT. 
The official heads of the two cooperating institutions, Dr. W. H. 
jordan of this Station and Dr. James Law of the New York State 
Veterinary College, have taken a keen and inspiring interest in the 
work here reported and we desire to record our appreciation of 
the value of their suggestions and advice in connection with the 
same, 
PRESNATOURE Os? UBERCULOSIS. 
Tuberculosis is a specific infectious disease. It is specific because 
it is produced by a single cause, the tubercle bacillus; it is infec- 
tious because this organism gets into the animal body and multi- 
plies there. It affects the animal by growing into the tissues and 
actually destroying the organs of the body that are necessary to 
the life of the individual, such as the liver, lungs and other vital 
parts. Although the course of the disease is often very chronic, 
it possesses all of the characters that determine an infectious malady. 
Because of its insiduous nature and slow development, cattle owners 
are very liable to ignore the essential conditions in its, dissemination 
and thereby often expose their herds to this most destructive of 
cattle diseases. | 
The two most important facts to know about an infectious dis- 
ease are, (1) how the micro-organisms that cause it escape from 
the diseased animal and (2) how the sound animals become 
infected. The answers to these questions relative to bovine tuber- 
culosis are for the greater part not uitficult. 
The tubercle bacteria escape from a tuberculous animal when 
the tissues they have destroyed are being discharged from the 
body. If the lungs are affected the dead particles of tissue, laden 
with tubercle bacilli, escape into the bronchial tubes and after 
being coughed up into the mouth they leave the body with the 
saliva. In these cases the tubercle bacteria can be found in the 
saliva that is left on the surface of the water in watering troughs 
or on the bottom of the mangers.’ If the tissues attacked happen 
to be glands in the walls of the intestine the dead particles of 
* Ravenel, M. P. The dissemination of tubercle baciclli by cows in coughing 
a possible source of contagion. University (Penn.) Medical Magazine, 
November, 1900. 
