CHAPTEE XIII. 



Inoculation of animals — Subcutaneous inoculation, intra-venous 

 injection. 



After subjecting an organism to the methods of study 

 that we have just reviewed, it remains that its action 

 upon the lower animals should be tested — i. e., to deter- 

 mine 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. 



This is commonly determined by both subcutaneous 

 and intra-venous inoculation. 



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 dirty it may be scrubbed with soap and water. 

 Disinfection of the skin is impossible, so that it need not 

 be attempted. If the inoculation is to be by means of a 

 hypodermatic syringe, then a fold of the skin may be 

 lifted up and the needle inserted in the way common 

 to this procedure. If a solid culture is to be inocu- 

 lated, a fold of the skin may be taken up with the 

 forceps and a pocket cut into it with scissors which have 



