364 AGRICULTURAL BACTERIOLOGY. 



certainly inviting tuberculosis, and bringing his animals into a 

 condition where they are sure to yield to the infection the first 

 time that chance brings the bacillus in their vicinity. More 

 outdoor life and more air are the prerequisites for a healthy herd. 

 The owner of cattle should also remember that anything 

 which will induce a vigorous life will decrease the tendency to 

 the disease. Proper food is an important factor in determin- 

 ing health, and, beyond doubt, the animals ought to have 

 exercise. It may be impossible under the conditions of 

 modern farming to allow the cattle to have exercise in the 

 winter, but the lack of it is certainly one of the factors tend- 

 ing to increase the liability to tuberculosis. It must also be 

 remembered that too great attention paid to the increase of 

 the yield of milk lessens the resisting power of cattle. Our 

 agriculturists, by over-feeding with certain kinds of food, and 

 by special high breeding for the purpose of increasing the 

 yield of milk, are trying to make a milking machine out of the 

 cow, instead of a normal animal, and it is quite likely that 

 this breeding out of normal characters has increased the 

 tendency to yield to tuberculosis. The highly bred animals 

 are, of course, too useful for the purpose for which they are 

 bred, to be given up, but the agriculturist must remember 

 that he cannot turn his cow into a simple milk-making ma- 

 chine, without suffering some evil results from the change in 

 her nature. In short, if the cattle owner will learn that cattle 

 are animals and not machines, and that they need something 

 besides food and water to keep them active, he will probably 

 soon find the tendency to tuberculosis becoming less. 



PROTECTION AGAINST INFECTION. 



But while the foundation of a healthy herd must be a re- 

 gard for the cow as an animal, it must not end here. Methods 

 of guarding the animal against infection are of the greatest 

 usefulness. While we cannot hope that it will ever be pos- 



