EXPERIMENTATION UPON ANIMALS. 



161 



or so and then separated. By this maneuver a subcuta- 

 neous pocket is formed, into which the tissue is easily 

 forced. The opening should not be large enough to re- 

 quire subsequent stitching. 



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 Fig. 42. 



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 

 is u much the same as if one would inject through a fire- 

 hose three or four quarts of some liquid into the respira- 

 tory organs of a man. ' ' 



The blood of animals, when it is necessary to experi- 

 ment with it, is best secured from 

 a large vein, generally the jugu- 

 lar. From small animals, such as 

 guinea-pigs, it may be secured by 

 introducing a small cannula into 

 the carotid artery. 



Our observations of animals by 

 no means cease with their death. 

 Indeed, he cannot be a bacteriol- 

 ogist who is f not already a good 

 pathologist and expert in the recog- 

 nition of diseased organs. 



When an autopsy is to be made 

 upon a small animal, it is best to 

 wash it for a few moments in a 

 disinfecting solution, to kill the 

 germs present upon the hair and the skin, as well as to 

 moisten the hair and enable it to be kept out of the 

 incision. 

 11 



FIG. 42. Mouse-holder. 



