86 AGRICULTURE OF MAIXE. 



from the diseased animals? In two or three ways generally. 

 Here is an animal with the disease confined, we may say, to 

 the lymphatic gland in the side of the neck ; that animal may 

 live in that condition for years and not infect any other animals. 

 The disease is confined to that gland, and there is no channel of 

 connection between that gland and the outside air. Xo germs 

 are being cast off. This animal will stand side by side with 

 other animals for years and the other animals not become affect- 

 ed. A little later the disease spreads and the lungs become 

 affected. We have a little tubercle growing by the side of the 

 air tube in the lung. This degenerates, breaks down, and pus 

 is coughed out. Here we have the germs coming out in mil- 

 lions. Another way, — these germs set free in the udder of the 

 cow are taken out in the milk by the calf and the calf gets the 

 disease directly from the dam. Wherever a tubercle degen- 

 erates in connection with a passage of the animal that communi- 

 cates with the outside air, whether it be in the lungs or in the 

 digestive tract or in the udder, the germs are set free from the 

 animals. We may have animals that for a long time are not 

 infecting others in the herd. Suddenly a tubercle degenerates, 

 and the germs are set free. Then it becomes a menace to every 

 animal. We find some animals that are constantly a menace 

 because we find sores in the lungs constantly giving off these 

 germs. The animals are coughing them out, they are falling 

 on to the food, they are drying and flying in the air and other 

 animals are breathing them in. These are a menace to the other 

 animals. 



Now, there has been more or less said about the infectedness 

 of milk from tuberculous cattle, and the statement has some- 

 times, even recently, been made that cattle never give off germs 

 through the milk unless they are diseased in the udder. That is 

 a theory that was considered well founded at one time, but that 

 question has been studied very carefully and statistics are not 

 lacking to show that any cow, we may say, that has tuberculosis 

 in any stage, may at any time give off germs in the milk. Xow 

 that is a broad statement, but I have given it guardedly. Any 

 cow affected with tuberculosis at any time may give off the dis- 

 ease germs in the milk. When we consider the probability, it 

 is very evident that with open sores in the udder the germs must 



