INOCULATION OF ANIMALS 75 



CXXXIX. INTRAVENOUS METHOD. 



In the rabbit this operation is generally performed in one of the 

 veins of the ear, and the most suitable vein is the ramus lateralis 

 posterior of the vena auricularis posterior, a very fine, delicate vessel 

 running along the posterior margin of the ear ; and being firmly fixed 

 in the dense surrounding tissue, it does not roll about when you are 

 inserting the needle. The largest branch of the vena auricularis 

 posterior is the central branch, or ramus anterior, but the insertion of 

 a needle into this vessel is accomplished with difficulty. 



If there is only a little blood in the ear, pressure at the root of 

 the ear will cause stasis of the blood and distension of the vessels, 

 rendering them more visible. Another method of rendering a vein 

 more prominent is to lightly press or gently prick with the point of a 

 needle the skin over the vessel to be used. The injection is always 

 made from the dorsal surface of the ear. Needles employed for intra- 

 venous injection must have a perfectly flat slanting surface free from 

 curvature. 



Care must be taken that no air is injected, and that the syringe 

 and needles are sterilized, before use, in the steam sterilizer or in 

 boiling water. The inoculated animal must be kept under close 

 observation for an hour after the operation. 



The syringes generally used are Koch's, Strohschein's, and Over- 

 lack's ; but the latter is preferred, as the dose can be controlled with 

 accuracy owing to the amount of air between the fluid and the piston 

 being at a minimum. 



CXL. INOCULATION INTO THE LYMPHATIC 

 CIRCULATION. 



Fluid cultures or suspensions of bacteria can be injected into the 

 lymphatics by way of the testicles, by plunging the point of the 

 needle into the substance of the testicle and injecting the desired 

 amount of fluid. 



CXLI. INOCULATION INTO THE GREAT SEROUS 



CAVITIES. 



To inject fluid into the peritoneum, make a small nick through 

 the skin, and plunge the needle direct into the peritoneal cavity. 

 There is not much danger of wounding the intestines and other 



