BLOOD AND GLANDS 401 



and blood-forming organs, but also for the nervous system, in 



which it gives the best and most constant coloration of the Nissl 



bodies. It colours also Rickettsia bodies, bacteria, and various 



pathological inclusions, such as vaccine bodies, Negri bodies, 



etc. Wolbach's (Journ. Med. Res., xli, 1919, p. 76) method, 



slightly modified, is recommended. 



Tissues are fixed in any of the usual mercuric chloride fixatives. 



Very good results are obtained using Maximow's Zenker formol 



(§ 78), six hours' fixation being ample. Sections 5 ft in thickness, 



or less, are passed down to water and are treated with Lugol's 



solution to remove the sublimate, followed by 0-5 per cent. 



sodium hyposulphite to remove, in turn, the iodine. They are 



then washed in distilled water. Stain twelve to twenty-four hours 



in : 



Distilled water . . . . .50 c.c. 



0-5 per cent, sodium bicarbonate . . 2 drops. 



Methyl alcohol, pure . . . .1-5 c.c. 



Giemsa's liquid stain (Griibler) . . 1-25 ,, 



The addition of methyl alcohol retards or prevents precipitation 

 of the dye. Differentiate in 95 per cent, alcohol, dehydrate, 

 clear and mount in cedar oil or any neutral mounting medium. 



If the cytoplasmic structures under investigation are too blue 

 (as may be the case if the material has been preserved in formalin 

 instead of Zenker's fluid) omit the sodium bicarbonate and add a 

 little colophonium to the alcohol used in differentiation, or 

 mordant before staining 2-5 per cent, potassium bichromate, or 

 employ a special stain with more of the Azur II. eosin and less of 

 the Azur II. component. If, on the other hand, they are too 

 red, either treat the tissues before staining with 1 per cent, 

 potassium permanganate, followed by 5 per cent, oxalic acid, or 

 else make up a sample of stain containing a higher concentration 

 of the red constituent (Azur II.). In general the pJI of both the 

 staining fluid and that used in washing should be 6-8 to 7-1. This 

 may be obtained by using the following buffering solution : KH2PO4 

 1 grm.. Nag HPO4 2 grm., distilled water 1 litre. With increased 

 pH there is increase in the bluish and decrease in the reddish 

 staining, lower values having the contrary effect. 



Canti {Journ. of Path, and Bact., 1935, xl, p. 233) uses Giemsa's 

 solution diluted in this buffer solution in the proportion of 2 drops 

 to 1 c.c. for the staining of virus bodies in tissue cultures. For 

 further information on the effect of hydrogen ion concentration 

 on staining, the papers of Mommsen {Klin. Woch. Jahrg., 1926, v, 

 p. 844) ; La Corte (C. R. Soc. Biol., Ixxxxviii, 1928, p. 1579) ; 

 French {Stain Tech., vii, 1932, p. 108) ; Ochs {Folia Hcemat., 

 xxvii, 1928, p. 241) should be consulted. 



McNamara {Journ. Lab. and Clin. Med., xviii, 1933, p. 752) 

 gives a rapid Giemsa stain for sections. 



