BLOOD AND GLANDS 397 



Scott {Journ. of Path, and Bad., vii, 1900, p. 131) exposes 

 films to the vapour for about five seconds and drops into absolute 

 alcohol, and after fifteen minutes stains and mounts. 



A short exposure (thirty seconds) to vapour of osmium has also 

 been recommended. 



SzECSi {Deutsch. vied. Wochschr., 1913, p. 1548) has recom- 

 mended Lucidol for blood smears, and smears of faeces containing 

 protozoa and cysts. The formulae for an acetone and pyridin 

 solution will be found in § 110, and also of an acetone xylol solu- 

 tion for subsequent washing of the smears. 



It is best to keep a sufficient quantity of the fixing solution in 

 staining jars. Make a smear, allow it to dry, and place it in the 

 acetone peroxide of benzol solution for fifteen minutes ; transfer 

 to the acetone xylol solution for ten minutes in order to remove 

 the lucidol ; wash off in pure methyl alcohol ; the slide is now 

 ready for staining. It will be found that most of the current 

 stains used for such smears will act successfully after the lucidol 

 fixation. Pappenheim's panoptic method (§ 879) is recommended. 



For smears of faeces a fixation of twenty minutes in pyridin 

 benzol peroxide solution is used ; wash as above, in acetone 

 xylol, or pyridin xylol, and then in methyl alcohol. 



Possibly the substitution of pure acetone for the methyl alcohol 

 bath might prove advantageous in some ways. 



In stains of the Romanowsky group, Jenner, Leishmann and 

 Wright, fixation is accomplished by the methyl alcohol of the 

 undiluted stain. Preliminary fixation is necessary in the case 

 of Giemsa staining. Pure absolute methyl alcohol is to be regarded 

 as one of the most satisfactory fixatives for dry blood films. Two 

 to five minutes is sufficient. Absolute ethyl alcohol may be used 

 but is not so good. The fixation time should then be greatly 

 increased. Thirty minutes or more. 



872. Stains of Blood. Fresh unfixed blood may be stained by 

 some dye contained in a diluting fluid, or by a dye deposited on 

 the surface of a slide in which the liquid blood is later placed. The 

 former method is largely used in the enumeration of leucocytes, 

 their nucleus being stained by some dye such as gentian violet 

 in the following commonly used solution given by Price-Jones 

 {Clinical Hmmatology, 1933), in which the cells are both fixed and 

 stained : 0-8 per cent, sodium chloride, 90 c.c. ; 40 per cent, 

 formol, 10 c.c. : gentian violet, a few drops. Supravital staining of 

 neutral red bodies or of mitochondria in leucocytes is carried out 

 by the latter method. Simpson {Journ. Med. Res., 1922, xl, p. 77) 

 makes saturated solutions for neutral red and Janus green B in 

 95 per cent, ethyl alcohol. Slides are prepared by dipping in the 

 mixture, after which they are allowed to dry. A drop of blood 

 is placed on a coverslip, mounted on a prepared slide and ringed 

 with paraffin. The glassware should have an even surface, and 



