KENAUT'S HJIMATOXYLIC EOSIN. 157 



249. Carmine and the Metallic Stains. These combinations 

 have been sufficiently spoken of in the passages devoted to 

 gold and silver impregnation-methods. It will suffice here to 

 call renewed attention to ZOLTAN v. ROBOZ, alum-carmine and 

 osmic acid ( 155). 



Combinations having Hsematoxylin for a Primary Stain. 



250. HaBxnatoxylin and Picric Acid. This excellent combina- 

 tion has been treated of above ( 236). See also 239. 



251. Haematoxylin and Eosin. This is a well-known com- 

 bination, and one of the most instructive that have yet been 

 imagined, though many workers prefer the combination of 

 haematoxylin with Benzopurpurm ( 133). Objects may be 

 stained with haematoxylin (either in the mass or as sections), 

 and the sections stained for a few minutes in eosin. I think 

 it is better to take the eosin weak, though it has been recom- 

 mended (STOHE, see Zeit.f. wiss. Mik., i, 1884, p. 583) to take 

 it saturated. Either aqueous or alcoholic solutions of eosin 

 may be used. 



This method is most particularly recommendable for embryo- 

 logical sections, as vitellus takes the eosin stain energetically, 

 and so stands out boldly from the other germinal layers in 

 which the blue of the haematoxylin dominates. 



LIST (Zeit.f. wiss. Mik.,ii, 1885, p. 148) stains for twenty-four 

 hours in a solution of three or four drops of Renaut's haema- 

 toxylic glycerin ( 189) in 250 c.c. of water, and then 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 (VerJi. Berl. Phys. Ges., 1877; GIERKE, Zeit.f. wiss. 

 Mik., 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 haematoxylin. 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 hsematoxylin or the 

 reverse, as eosin very easily precipitates haematoxylin. 



252. Renaut's Hsematoxylic Eosin (Foi/s Lehrbuch, p. 196). 

 Kenaut has given from time to time several formulae for this 



