Specific Contagious Diseases. 139 



T0BEECULOSI8. CONSUMPTION'. PmniTG. 



This is a specific bacteridian affection, due to a bacillus, and 

 cliaracterized by a specific deposit of cells, large and small, 

 in a special network, but without blood-vessels. It is situ- 

 ated by preference in the groups of lymphatic glands, or in 

 the microscopic gland-like tissue of the different organs, and 

 may be seen in all stages, from the simple redness and con- 

 gestion in which tlie deposit is only commencing, through 

 the solid grayish tubercle to the soft yellowish, cheese-like 

 mass resulting from the softening of the latter. There are 

 also tlie open cavities {vomicce) resulting from their rupture 

 and discharge of the tuberculous matter, and chalky masses 

 from the deposit of earthy salts within them. They may 

 be no larger individually than a millet-seed (miliary tuber- 

 culosis), or in the chest of cattle one may measure a foot 

 long and five or six inches in thickness. They are most 

 common in cattle, especially heavy milkers, with long legs, 

 narrow chest, attenuated neck and ears, and horns set near 

 together. Fowls and swine with a corresponding conforma- 

 tion are next in order of liability, while horses, dogs, and 

 slieep are comparatively exempt. Oft-repeated experiment 

 has shown that tubercle is communicable to healthy animals 

 by inoculation, or by eating the raw, diseased product, and 

 that it is supei'induced in any predisposed individual by set- 

 ting np a local inflammation. It has also been transmitted 

 by the warm, fresh milk, but probably only when the dis- 

 ease has invaded the mammary glands ; in many experi- 

 ments, including those conducted by the author, the milk 

 has proved harmless. Close, badly-aired buildings (as town 

 cow-sheds) are among the most prolific causes of the disease, 

 as are also changes to a colder climate, to a cold, exposed 

 locality, or from a dry to a low, damp, undrained region. 

 Finally, any cause which tends to wear out the general 

 health tends to tuberculosis in a predisposed subject. 



