316 DR. LEGEAR'S STOCK BOOK. 



ea>e is transmissible from one animal to another of the same 

 species, and from one species to another. No matter how the 

 germs may enter the system, whether inhaled, taken in with food 

 or inoculated, the disease is liable to ensue. A consumptive ani- 

 mal placed among animals communicates the disease to those 

 previously healthy. Milk from an affected cow fed to cats, 

 calves, hogs, guinea pigs, etc., produces the disease in them. In- 

 oculating the infected milk into other animals produces the dis- 

 ease. Sputa coughed up by man and carelessly spit out has been 

 licked up and devoured by animals and produced the disease in 

 them. 



When the stomach, intestines and mesenteric glands are dis- 

 eased, it is probably the result of food infection. The germs of 

 the disease may have been scattered upon the feed by diseased 

 animals. But the milk of consumptive cows is the most common 

 source of such infection. Calves may become infected in this 

 way, and the disease may not develop until the animal becomes 

 older. 



Up to a recent period the opinion prevailed that it was only 

 milk from cows with diseased udders that was extremely dan- 

 gerous, but the experiments of Professor Ernst of Harvard Uni- 

 versity and many others have demonstrated the fact that milk 

 from a consumptive cow may contain the germs, even though the 

 udder is absolutely free from disease. 



While we believe in the germ theory, yet there are conditions 

 which must be recognized as almost necessary to an attack of the 

 disease. Unsanitary conditions, such as overcrowding in poorly 

 ventilated and lighted stables, and feeding of food that is not 

 nutritious are conditions which favor the germs in their attack. 

 Any injury to the lungs such as inhalation of dust and smoke 

 and all conditions which may induce chronic inflammation of 

 the bronchial tubes. 



Of all points in the subject none seem to be more assailed than 

 heredity. There has been no positive proof of tin- disease having 



