126 COMBINATION STAINS. 



for a few minutes in a mixture of one part of 0'5 per cent, 

 aqueous solution of eosin with three parts of absolute alcohol. 



BUSCH (Verh. Berl. Phys. Ges.. 1877; GIEKKE, Z&tt. f. wiss. 

 Mik.j i, 1884, p. 505) treats sections for some days with 0*5 

 per cent, solution of chromic acid, or 1 per cent, solution of 

 bichromate of potash, washes, and stains first in an aqueous 

 solution of eosin and then in hasmatoxylin. This process has 

 been recommended for the study of the margin of ossification. 



It should be noted that sections should be very well washed 

 before being passed from eosin into hasmatoxylin or the 

 reverse, as eosin very easily precipitates hsematoxylin. 



239. Renaut's Haematoxylic Eosin (Foi/s Lehrbuch, p. 196. 

 Renaut has given from time to time several formulae for this 

 stain. This one, communicated to Fol by Renaut, is the 

 latest, and I suppress the others). 

 Take 



Concentrated aqueous solution of potassic eosin 



(eosine a la potasse) . . . . . 30 c.c. 



Saturated solution of haematox. in alcohol (ought 

 to have been kept some time and to have pre- 

 cipitated) . . . . . . .40 c.c. 



Saturated solution of potash alum in glycerin 



(of a density of about 1*26) . . . 130 c.c. 

 Mix, and let the mixture stand five or six weeks in a vessel 

 covered with a sheet of paper pierced with holes until the 

 alcohol is evaporated, then filter. 



For staining, the solution may be used as it is or diluted. 

 Staining goes on very slowly, and at first the colour is not 

 held by the tissues, but disappears on washing. After some 

 days or weeks, however, it becomes localised and fixed in the 

 tissues. You may then mount in balsam, taking care to 

 employ alcohol charged with a sufficient quantity of eosin. 

 But it is frequently preferable to proceed by mounting the 

 objects in the staining fluid diluted with one to two volumes 

 of glycerin. After a few weeks this mounting medium will 

 have become perfectly colourless through the absorption of 

 the colour by the tissues. 



The stain has a specific action on the cells of salivary and 

 gastric glands. Mucous-cells become pale blue. Salivary 

 ferment-cells (crescent-cells of Grianuzzi) intense rose. 



