CHAPTEE X. 



EXPEKIMENTS UPON ANIMALS. 



THE inoculation of animals with the germs of various infec- 

 tious diseases has been the means of enabling us to observe 

 accurately and to record the progressive growth and develop- 

 ment of pathogenic bacteria in the living body and the con- 

 ditions resulting therefrom. Animal experimentation has 

 been of inestimable value in medicine, especially in physi- 

 ology, materia medica, therapeutics, and bacteriology. In 

 bacteriology it is an aid in the diiferentiation and detection of 

 bacteria as well as in the determination of their pathogenicity. 



White mice, guinea-pigs, rabbits, and monkeys are the 

 animals usually used for this purpose. They are of a size 

 that will not interfere with the work ; they can be kept in 

 the laboratory; and they are also very susceptible to the 

 various infectious diseases. 



We must, however, remember that some animals possess a 

 natural immunity or resistance to certain diseases, and cannot 

 be used for work connected with such diseases. 



The animals should be kept in a clean wire cage in a light, 

 well- ventilated room. They should have plenty of good food 

 and fresh water, and every care taken of them. The experi- 

 ments should be performed with the same care as an opera- 

 tion for such the experiments really are on the human 

 being. Careless and negligent handling of these animals is 

 not only unpardonable, but also unnecessary. 



The inoculations may be made directly into a vein (intra- 

 venous injection) ; into the subcutaneous tissues ; or into the 

 peritoneal cavity. 



It is preferable to use a syringe that can be sterilized 

 easily. Koch's syringe is used more than any other. It con- 

 tains no piston, the contents being forced out with a rubber 

 bulb ; and when this bulb is removed, it can be sterilized by 



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