known order, and a blank one added at the last, 

 to avoid the possible mistake of reversing the series. 

 A few minutes is all that is necessary if one is in a 

 hurry. Otherwise they may be left in from one- 

 half to twenty-four hours as may be convenient. 

 They are then taken out, allowed to dry, and 

 placed in series in a slide-box, and labelled as 

 desired. 



There is the possibility that absolute alcohol 

 may not at times be obtainable. Other fixing 

 methods are :— 



1. Methylated spirits. (This is in fact quite 

 adequate for the fixing of blood films in the 

 absence of absolute alcohol). 



2. By the use of Leishman's stain. (The 

 stain itself contains the fixative). 



3. By heat. Heating to 100° -110° for five 

 minutes on a copper plate gives very beautiful 

 leucocyte preparations with Ehrlich's stain. This 

 method requires care, and a copper plate for 

 heating the slides. If greatly pushed, one may 

 often satisfactorily fix by passing the slides several 

 times through the flame of a spirit lamp. 



4. For other methods, vide Appendix. 



To Stain Films 



A large choice of methods is usually given for 

 the demonstration of the malarial parasite in 

 blood. There is one stain, however, so much 

 more strikingly effective and generally satisfactory 

 than other stains that, for routine use, no alter- 

 native method need be considered. This stain is 

 Romanowsky's chromatin stain ; the modifications 

 of Leishman will also be found simple and certain. 



