68 ESSENTIALS OF BACTERIOLOGY. 



suffering from tuberculosis, were cured ; control animals dying. 

 Koch, in 1890, applied this method to man, and the final results 

 are still sub juclice. 



Koch's Rules in Regard to Bacterial Cause of Disease, 

 Before a microbe can be said to be the cause of a disease, it 

 must 



First. Be found in the tissue or secretions of the animal suf- 

 fering from, or dead with the disease. 



Second. It must be cultivated outside of the body on artificial 

 media. 



Third. A culture so obtained must produce the disease in 

 question when it is introduced into the body of a healthy 

 animal. 



Fourth. The same germ must then again be found in the 

 animal so inoculated. 



CHAPTER XV. 



EXPERIMENTS UPON ANIMALS. 



THE smaller rodents and birds are the ones usually employed 

 for inoculation, as rabbits, Guinea-pigs, rats and mice, and 

 pigeons, and chickens ; sometimes monkeys. These are pre- 

 ferred, because easily acted upon by the various bacteria, readily 

 obtained, and not expensive. 



The white mouse is very prolific and easily kept, and is there- 

 fore a favorite animal for experiment. It lives well upon a little 

 moistened bread. A small box, perforated with holes, is filled 

 partly with sawdust, and in this ten to twelve mice can be kept. 

 When the female becomes pregnant she should be removed to 

 a glass jar until the young have opened their eyes, because the 

 males, which have not been raised together, are apt to attack 

 each other. 



Guinea-pigs. When Guinea-pigs have plenty of light and 

 air the} r multiply rapidly. Therefore it is best to have them in 

 some large stall or inclosure. They can be fed upon all sorts of 

 vegetables and grasses, and require but little attention. 



