242 BACTERIOLOGY. 



distant. When pigeons are used they are held with the 

 legs, tail, and ends of the wings in the one hand, and 

 the head and anterior portion of the body in the other, 

 leaving the area occupied by the pectoral muscles, over 

 which the inoculation is to be made, free for manipu- 

 lation. In the case of fur-bearing animals the hair over 

 the point selected for the inoculation should be closely 

 cut with scissors, and from a small area the feathers 

 should be plucked in the case of birds. 



INJECTION INTO THE CIRCULATION. It is not in- 

 frequently desirable to inject the material under consid- 

 eration directly into the circulation of an animal. If 

 a rabbit is employed for the purpose, the operation is 

 usually done upon one of the veins in the ear. To those 

 who have had no practice with this procedure it offers a 

 great many difficulties ; but if the directions which will 

 be given are strictly observed, the greatest of these 

 obstacles to the successful performance of the operation 

 may be overcome. 



When viewing the circulation in the ear of the rabbit 

 by transmitted light three conspicuous branches of the 

 main vessel (vena auricularis posterior) will be seen. 

 One runs about centrally in the long axis of the ear, 

 one runs along its anterior margin, and one along its 

 posterior margin. The central branch (ra/mus anterior 

 of the vena auricularis posterior) is the largest and most 

 conspicuous vessel of the ear, and is, therefore, believed 

 by the inexperienced to be the branch into which it would 

 appear easiest to insert a hypodermic needle. This, 

 however, is fallacious. This vessel lies very loosely 

 imbedded in connective tissue, and, in eiforts to intro- 

 duce a needle into it, rolls about to such an extent that 

 only after a great deal of difficulty does the experiment 

 succeed. On the other hand, the posterior branch (ramus 



