60 



TECHNIC OF ANIMAL INOCULATION 



Mice and Rats. 1. Mice and rats may be injected through a 

 caudal vein of the tail. These veins are quite small, and the injection 

 requires a fine needle and some experience in the manipulations. 



2. Fasten the mouse 

 in a special trap, so 

 that the tail alone will 

 be exposed. Grasp the 

 tip between the left 

 thumb and index- 

 finger, and hold the tail 

 fully extended. 



3. A caudal vein is 

 rendered prominent by 

 the gentle application of 

 heat in the form of hot 

 water, or by vigorous 

 rubbing with xylol or al- 

 cohol. The superficial 

 cells become softened, 

 and may be scraped off 

 with a sharp scalpel, 

 exposing a vein on each 

 side of the middle line 

 of the tail. 



4. It is usually ad- 

 visable to have an as- 

 sistant steady the tail 

 while the inoculation is 

 being given; a fine 

 needle is essential. In- 

 oculation should begin 

 as near the tip of the 

 tail as possible, and in 

 subsequent inoculations 

 gradually approach the 

 root (Fig. 31). 



5. Rats may also be injected through the external jugular vein, in 

 exactly the same manner as a guinea-pig is inoculated. (See Fig. 30.) 

 The animal is fastened to a small operating board, and an assistant 

 holds the head to the left, which stretches the tissues of the right shoulder 



FIG. 31. METHOD OF INTRAVENOUS INOCULATION OF 



a RAT. 



The hairs and superficial layers of the skin have 

 been scraped away with a scalpel. The vein on each 

 side of the middle line appears as a bluish line in the 

 subcutaneous tissues. 



