CHAPTER XII. 



Inoculation of animals — Subcutaneous inoculation ; Intra-venous injection 

 — Inoculation into the great serous cavities ; and into the anterior chamber of 

 the eye— Observation of animals after inoculation. 



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 means of deciding these points is by inoculation, 

 which is practised in different ways according to cir- 

 cumstances. Most commonly a bit of the culture to be 

 tested is simply introduced beneath the skin of the 

 animal, but in other cases it may be necessary to intro- 

 duce it directly into the vascular circulation 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. 



Subcutaneous Inoculation or Animals. — The 

 animals usually employed in the laboratory for purposes 

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

 pigs, rabbits, and pigeons. 



For simj^le 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 



