LESSON xi CULTIVATIONS FROM DEAD ANIMALS 133 



(a) Prepare three gelatine plates severally from the 

 spleen, peritoneal fluid, and heart's blood in the ordinary 

 manner, and place them in the cool incubator. 



(b) Also make agar-agar streak cultures from the spleen 

 of the mouse, and from the peritoneal fluid of the guinea- 

 pigs (vide p. 106). 



Place these in the warm incubator. 



The plates and agar-agar tubes should be worked up 

 in the usual manner. 



(c) Prepare also cover-glass specimens of the spleen and 

 peritoneal fluid, and stain them with Loffler's methylene- 

 blue, and examine them with -^ in. oil immersion. 



Quick Method of Hardening and of Embedding 

 in Paraffin 



(1) Place small pieces of the mouse's spleen, kidney, 

 liver, and lung in absolute alcohol. 



(2) Change the alcohol every half -hour, using always an 



excess. 



(3) After one and a half to two hours place the small 

 pieces of tissue in a small corked bottle containing benzol, 

 till they are transparent (a few minutes). 



(4) Now pour off the excess of benzol, so that the pieces 

 are only just covered by it, add a few shavings of paraffin 

 (56 to 60 C. melting point), and place the bottle on the 

 paraffin stove, till the paraffin liquefies. 



