CHAPTER XII. 



Inoculation of animals — Subcutaneous inoculation — Intravenous in- 

 jection — Inoculation into the great serous cavities, and into the 

 anterior chamber of the eye — Observation of animals after inocu- 

 lation. 



After subjecting an organism to the methods of 

 study that we have thus far reviewed there remains to 

 be tested its action upon animals — i. e., to determine if 

 it possesses the property of producing disease or not ; 

 and, if so, what are the pathological results of its 

 growth in the tissues of these animals, and in what way 

 must it gain entrance to the tissues in order to produce 

 these results ? The mode of deciding these points is by 

 inoculation, which is practised in different ways accord- 

 ing to circumstances. Most commonly a bit of the cult- 

 ure to be tested is simply introduced beneath the skin 

 of the animal ; but in other cases it may be necessary 

 to introduce it directly into the vascular or lymphatic 

 circulati(_)n, or into one or the other of the great serous 

 cavities ; or, for still other purposes of observation, into 

 the anterior chamber of the eye, upon the iris or within 

 the skull cavity, upon the dura or brain substance. 



Subcutaneous Inoculation of Animals. — The 

 animals usually employed in the laboratory for purposes 

 of inoculation are white mice, gray house-mice, guinea- 

 pigs, rabbits, and pigeons. 



For simple subcutaneous inoculation the steps in the 

 process are practically the same in all cases. The hair or 

 feathers are to be carefully removed. If the skin is very 

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