USE OF AMMALS FOR DIAGNOSTIC AXD TEST PURPOSES 137 



cent, solution of carbolic acid. All instruments are sterilized by I >< til- 

 ing in 3 per cent, soda solution for five minutes. Changes of knives, 

 scissors, and forceps should be made as frequently as the old ones 

 become infected. When organs are examined the portion of the sur- 

 face through which an incision is to be made must be sterilized, if 

 there is danger that the surrounding cavity is infected, by searing with 

 the flat blade of an iron spatula which has been heated to a dull-red 

 heat. Tissues if removed should be immediately placed under cover 

 after removal so as not to become infected. Sterile deep Petri plates 

 are useful for this purpose. 



When it is necessary to transport tissues some distance they should 

 be wrapped in bichloride cloths and sent to the point of destination 

 as soon as possible. In warm weather they may be kept cool by sur- 

 rounding the vessel which contains them with ice. 



Animals rarely show the same gross lesions as man when both suffer 

 from the same infection. The cell changes are similar, and, also, so far 

 as we can test them, the curative or immunizing effects of protective 

 serums. 



Leukocytes for Testing Phagocytosis. Inoculate into the pleural cavity 

 of a rabbit 5 c.c. of a thick suspension of aleuronat powder in a boiled 

 starch solution. The solution should be thick enough to hold the 

 aleuronat in suspension. A 20 to 25 per cent, solution of peptone 

 gives good results. The fluid is withdrawn eighteen to twenty-four 

 hours after the injection. 



