SECTION THREE 



of the sodium sulphate in the above recipe is extremely doubtful 

 and it appears that this constituent may be left out without any 

 noticeable effect. 



Petrunkevitch's Cupric Paranitrophenol Fixative 

 (Petrunkevitch, 1933) 



Recommended for : 

 Tissues in general. 



Recipe: 



Alcohol 60% 100 ml. 



Nitric acid, pure (sp. gr, 1-41 — 1-42) 3 ml. 



Ether 6 ml. 



Cupric nitrate Cu(N03) 2, 3H2O . . 2 gm. 



Paranitrophenol pure, cryst. . . 5 gm. 



Technique: 



Fix material for twelve to twenty-four hours. Wash in 70% 

 alcohol; dehydrate; clear and embed. 



Remarks: 



All stains commonly in use may be employed after this fixative, 

 which causes less hardening than most other fixatives. 



Regaud's Fluid 



Recommended for : 



Mitochondria and rickettsia in animal tissues. 



Recipe: 



Potassium dichromate . . • • 3 g^n* 



Distilled water 100 ml. 



Formalin (formaldehyde 40%) . . 25 ml. 



Technique: 



Fix material for three days changing the fluid every day. Im- 

 merse in 3% potassium dichromate for six to eight days; then 

 wash in running water for twenty-four hours.' Dehydrate; clear 

 and embed. 



Remarks: 



Suitable for Giemsa stain and for Masson's trichrome stain. 



483 



