lO 



In some circumstances the one will be found 

 more convenient ; in others, the other. Both 

 methods are therefore given. The making up of 

 the stain, although apparently rather complicated, 

 is not in reality so, and the staining of blood films 

 is one of the simplest, most rapid, and certain of 

 methods. It is useless to attempt to prepare the 

 stain unless suitable methylene blue and eosin are 

 obtained. These stains are very inexpensive, and 

 the only care necessary is to order the exact stain 

 from a good firm (C. Baker, 244 High Holborn, 

 London). 



By the use of Method 2, the staining of blood 

 films is so simplified that a bottle of stain and a 

 supply of water is all that is necessary for the pro- 

 cess. Process No. i, however, is in some ways 

 very convenient and rather more certain, and was 

 largely used by us. 



Method I. The following materials are 

 necessary for the making of the stain, viz : — 

 ' Medicinal ' methylene blue. 

 Eosin extra (B.A. or A.G.) or simply pure 



eosin for blood staining. 

 Sodium carbonate, pure. 



Two stock solutions are made : — 

 Solution A. Methylene blue . i"o part. 

 Sodium carbonate . o'5 parts. 

 Water . . .100 parts. 



The solution is then placed in a hot incubator 

 or by the kitchen fire, or in the tropical sun for 

 two or three days. By this time a deep-purple 

 colour will be noticed at the edges of the liquid. 

 The colour depends upon the formation of a new 

 red body which, combined with eosin, forms the 

 active staining principle of Romanowsky. Until 



