SECTION TWO 



C. Potassium dichromate 2-5% 



aqueous . . . . . . . . 88 ml. 



Sodium chloride 10% aqueous . . 7 ml. 



Note: Keep a few pieces of marble chips in 

 the bottle. 



D. Dichromate-formaldehyde. 



Solution B I volume. 



Solution C 19 volumes. 



E. Potassium dichromate 5% aqueous 



F. Gelatine for embedding. 



Gelatine powder . . . . . . 25 gm. 



Water . . . . . . . . 100 ml. 



Sodium p-hydroxybenzoate . . 0-2 gm. 



Sprinkle the gelatine on to the water and leave it to soak for an 



hour, afterwards warming in an incubator maintained at 37° C. 



until all the gelatine has dissolved, then strain through muslin while 



still warm. 



Note: If Sodium p-hydroxybenzoate, which is added to prevent 

 the growth of moulds and bacteria, is not available in the laboratory, 

 then 0-25 to 0*5 gm. of Thymol should be used instead. 



G. Formalum {for hardening gelatine) 

 Formalin (Formaldehyde 40%) . . 20 ml. 

 Potassium alum 5% aqueous . . 80 ml. 

 Keep marble chips in the bottle. 



Note: Both gelatine blocks and gelatine sections may be pre- 

 served indefinitely in Formalum, which makes the gelatine very 

 hard, thereby facilitating the cutting of thin sections which are 

 non-sticky. 



Important: Formalum must not be used in the acid haematein 

 test for phospholipids (Baker 1946) as the alum would react with 

 the haematein. 



H. Sudan Black ... ... . . 0-5 gm. 



Alcohol 70% 100 ml. 



Boil for ten minutes under a reflux condenser ; 

 then cool and filter. 



I. Car malum {Mayer). 



205 



