SUBCUTANEOUS INOCULATION. 187 



This is tacked upon the board in such a position that 

 its long axis runs in the long axis of the board, 

 being equidistant from its two sides. Its small end is 

 placed at the edge of the board. The mouse is taken up 

 by the tail by means of a pair of tongs and allowed to 

 crawl into the smaller end of this wire cone. When so 

 far in that only the root of the tail projects, the animal 

 is then fixed in this position by a clamp and thumb- 

 screw, with which the apparatus (Fig. 36) is provided. 

 The animal usually remains perfectly quiet and may be 

 handled without difficulty. 



Fig. 36. 



Mouse-holder, with mouse in proper positioD. 



The hair from over the root of the tail is to be care- 

 fully cut away with the scissors, and a pocket cut 

 through the skin at this point. The inoculation is 

 then made into the loose tissues under the skin over 

 this part of the back in the way that has just been 

 described. It is best always to insert the needle some 

 distance along the spinal column, and thus deposit the 

 material as far from the surface-wound as possible. 



As the subcutaneous operation is very simple and 

 takes only a few moments, guinea-pigs, rabbits, and 

 pigeons are best held by an assistant. The front legs 

 in the one hand and the hind legs in the other, with 



