CHAPTER IX. 

 EXPERIMENTATION UPON ANIMALS. 



BACTERIOLOGY has to-day become a science whose 

 principal objects are to discover the cause, explain the 

 symptoms, and prepare the cure of diseases. We can- 

 not hope to achieve these objects except by the intro- 

 duction of bacteria into animals, where their effects and 

 the effects of their products can be studied. 



No one should more heartily condemn wanton cruelty 

 to animals than the physician and the naturalist. In- 

 deed, it is hard to imagine a class of men so much of 

 whose lives is spent in relieving pain, and who know so 

 much about pain, being guilty of the wholesale butchery 

 and torture accredited to them by a few of the laity, 

 whose eyes, but not whose brains, have looked over 

 the pages of physiological text-books. 



Experimentation upon animals has given us almost 

 all our knowledge of physiology, most of our valuable 

 therapeutics, and the only scientific methods of treating 

 tetanus and diphtheria. 



Experiments upon animals we must make, and, as 

 animals differ in their susceptibility to diseases, large 

 numbers and different kinds must be employed. 



The bacteriological methods are not cruel. Two prin- 

 cipal modes of introducing bacteria are employed : the 

 subcutaneous injection and the intravenous injection. 



Subcutaneous injections into animals are made exactly 

 as hypodermic injections are given to man. 



The intravenous injections differ only in that the needle 

 of the syringe is introduced into a vein. This is easy in a 

 large animal like a horse, but is very difficult in a small 

 animal, and wellnigh impossible in anything smaller than 



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