DISEASES OF CATTLE 243 



is often greatly distended with gas. This, however, is not a very 

 frequent symptom. 



Diarrhea. Looseness of the bowels or scouring is seen in cattle 

 affected with the disease in the bowels. This kind of scouring can 

 not be cured by any known treatment. 



Hard Lumps on the Udder. When tuberculosis attacks the udder 

 no change can be detected at first, but after a time hard lumps can be 

 felt in some parts of the organ after it is milked out. Milk from 

 such an udder must not be used, as it is almost certain to be teeming 

 with germs of the disease. 



Post-mortem Appearances. When the carcass of a cow affected 

 with tuberculosis is opened the disease may be found in any part of 

 the body. Lumps (tubercles) may be present in the substance of 

 an organ such as the lung or liver, or they may be growing on the 

 surface. These lumps may be so small as to be scarcely noticeable, or 

 they may be as large as the closed fist, or even larger. If one of the 

 lumps is cut open, the inside is yellowish and grits on the knife like 

 sand, or else is of a cheesy nature, soft and creamy, or hard and dry. 



The lung is a favorite place for tubercles, and should always be 

 examined. Lymph glands are often the seat of tuberculous changes. 

 When healthy a lymph gland is a little rounded body not much 

 larger than a good-sized bean, the largest only the size of one's 

 thumb. They are found all through the body, and when healthy 

 are so small as to attract very little attention. Tuberculosis may 

 cause them to grow to an enormous size, sometimes as large as a 

 child's head. In this condition they are similar to the tuberculous 

 lumps already described. Those lying between the lungs and in the 

 throat are the most frequently affected. 



Tubercles may be found in any part of the body glands, lungs, 

 liver, bowels, kidneys, womb, udder, and even bones. The muscles 

 and skin are seldom affected. 



The Tubercle Bacillus. The germ of the disease, the tubercle 

 bacillus, is a tiny, slender, rod-shaped body. Several thousands of 

 them placed end to end would be needed to measure an inch, so that 

 they are quite invisible to tibe naked eye. A powerful microscope is 

 needed to see them. 



Once the bacillus has gained lodgment inside the body of an 

 animal, it begins to grow and multiply. It gets longer, and when 

 full grown divides crosswise, making two out of one. Each of these 

 goes through the same process, the two become four, the four eight, 

 the eight sixteen, and so on indefinitely. 



This multiplication takes place quite rapidly when conditions 

 are favorable, a few hours only being required for the birth of each 

 generation. Nature, however, does not permit this process to continue 

 long wfthout offering some resistance. The forces of the body are 

 aroused to action and a battle begins between the tissues of the body 

 and the army of the invaders. 



The first line of defense is composed of the white cells of the 

 blood, which hurry to the scene of action and endeavor to destroy 

 the invaders by eating them up. Sometimes they are successful and 



