EXPERIMENTATION UPON ANIMALS. 



135 



a rabbit. Such injections when given to rabbits are gen- 

 erally made into the ear-veins, as those most conspicuous 

 and accessible (Fig. 35). A peculiar and important fact 

 to remember is, that the less conspicuous posterior vein 

 is much better adapt- 

 ed to the purpose than 

 the anterior. The in- 

 troduction of the nee- 

 dle should be made 

 from the hairy surface 

 of the ear. 



Sometimes intra- 

 abdominal and intra- 

 pleural injections are 

 made, and in cases 

 where it becomes ne- 

 cessary to determine 

 the presence or ab- 

 sence of tuberculosis 



or glanders in tissues FlG - 35- Method of making an intravenous 

 ., r injection into a rabbit. Observe that the needle 



it may be necessary . . , . 



J J enters the posterior vein from the hairy surface. 



to introduce small 



pieces of the suspected tissue under the skin or into 



the abdominal cavities. 



Sometimes the inoculation can be made by the platinum 

 wire, a very small opening in the skin being sufficient. 



Small animals, like rabbits and guinea-pigs, can be 

 held in the hand, as a rule. Rabbit-holders of various 

 forms can be obtained from dealers. Dogs, cats, sheep, 

 and goats can be tied and held in troughs. A convenient 

 form of mouse-holder, invented by Kitasato, is shown in 

 Figure 36. 



In all these experiments one must remember that the 

 amount of material introduced into the animal must be 

 in proportion to its size, and that injection-experiments 

 upon mice generally are so crude and destructive as to 

 warrant the comparison drawn by Frankel, that to inject 

 a few minims of liquid into the pleural cavity of a mouse 



