INJECTION INTO THE CIRCULATION. 241 



of tongs and allowed to crawl into the smaller end of 

 the wire cone. When so far in that only the root of 

 the tail projects the animal is fixed in this position by 

 a clamp and thumb-screw, with which the apparatus 

 (Fig. 45) is provided. The animal usually remains per- 

 fectly quiet and may be handled without difficulty. 



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

 fully cut away with scissors and a pocket cut through 

 the skin at this point. The inoculation is then made 

 into the loose tissue under the skin over this part of the 

 back in the way that has just been described. It is 

 always best to insert the needle some distance along the 



FIG. 45. 



Mouse-holder, with mouse in proper position. 



spinal column, and thus deposit the material as far from 

 the surface-wound as possible. 



As the subcutaneous inoculation is very simple and 

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

 pigeons may be held by an assistant. The front legs in 

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

 animal stretched upon its back on a table, is the usual 

 position for the operation when practised upon guinea- 

 pigs and rabbits. The point at which the inoculations 

 are commonly made is in the abdominal wall, either to 

 the right or left of the median line and about 3 cm. 



16 



