8o AGRlCULTURli OF MAINE. 



and soft or hard as the case may be. These tubercles later may 

 run together and form large tubercular masses that may contain 

 solid matter. These may be found in the lungs, or in the lym- 

 phatic glands, or along the intestines, or in any part of the body. 



THE CAUSE OF THE DISEASE- 



The cause of tuberculosis was in doubt until 1881, when Prof. 

 Koch discovered it as a vegetable parasite, the tubercle bacillus, 

 and now we may say that tuberculosis in all animals, under all 

 the varying conditions, is due to this one vegetable organism. 

 There are other contributing causes, but the other causes may 

 be present, and this cause being absent we have no tuberculosis. 

 A tubercle bacillus so small that it requires to be magnified 

 three or four hundred diameters in order for us to see it, is the 

 cause of the trouble. How does this organism cause the trouble? 

 How are animals infected? The stable in which healthy animals 

 are living may be cold, it may be warm, it may be close, it may 

 be open, it may be damp, the conditions may be as bad as you 

 can imagine them, and the animals do not get tuberculosis. But 

 provided the germs of the disease are present, provided you have 

 one diseased animal in the herd, the other animals get the dis- 

 ease. Manifestly they must get it through some channel or 

 entrance into the body. The organism on the surface of the 

 body is not in a favorable condition to grow. It is simply a 

 particle of dust. But the animal has to eat and to breathe, and 

 in these natural functions the opening is made by which the 

 animal may become infected. The animal eats the germs, they 

 find their way into the body through the digestive tract. Ani- 

 mals may become infected, and do sometimes possibly, through 

 the milk ducts and through wounds in the surface of the body. 

 But practically, as we meet the disease, we find animals get it 

 in two ways, they either eat it or breathe it in. Now as these 

 germs enter the animals, in the food or air, they are simply 

 minute particles of dust, and are still, in a sense, outside of the 

 animal's body. They are simply in the passages that communi- 

 cate with the external air ; but when these germs find their way 

 into these passages, and rest on the mucous membrane, they have 

 the power of entering into the membrane. They may enter so 

 deeply that they find conditions favorable for their growth, viz. : 



