SPECIAL CONSIDERATIONS. 95 



If it is desired to make an inoculation directly into the 

 lymphatics, some organ with a very poor blood-supply should 

 be chosen. The choice is the testicle, the injection being 

 made deeply into the organ. 



Pasteur inoculated rabbits with hydrophobia virus by in- 

 jecting an emulsion of the spinal cord of an animal sick with 

 hydrophobia beneath the dura mater through a trephine-open- 

 ing made a short distance back of the eyes. 



For the purpose of studying the local effects of various 

 bacteria, inoculations are made into the anterior chamber of 

 the eye. An incision is made through the cornea with a 

 cataract knife and a liquid culture injected, or solid material 

 is introduced with the platinum needle or forceps. 



Special considerations : Injections may be made without the 

 use of an anaesthetic. Painful operations are made under 



FIG. 34. 



Mouse-holder, with mouse in proper position. 



ether anaesthesia. Chloroform is apparently not well borne 

 by animals. When the inoculation is to be made, the animal 

 is wrapped securely in towels, leaving the site of inoculation 

 exposed. An assistant holds the animal and keeps it from 

 struggling. Special holders (Figs. 34, 35, 36) have been de- 

 vised for the smaller animals. They are simple in construc- 

 tion, convenient, and inexpensive. 



Young animals are preferable to old ones. Intravenous 

 injections are the most fatal, and only a small dose of the 

 culture or suspected material should be injected. Peritoneal 

 injection produces results more rapidly than subcutaneous 

 injection. Virulent cultures should always be used. They 



