MINOT'S HJSMATOXYLIN METHODS. 97 



with alum solution (1 per cent.) instead of a chromate. La- 

 this case the stain will be blue. 



179. Apathy's Modification of Heidenhain's Process (Zeit. f. 

 wiss. Mik., v, I, 1888, p. 47). This is an alcoholic method. 

 Stain in a 1 per cent, solution of haematoxylin in 70 or 80 per 

 cent, alcohol. Wash out (for " thin " sections, i. e. sections of 

 10 to 15 /ui, half the time of staining for "thicker" sections 

 of 25 to 40 ju twice the time of staining) in 1 per cent, solution 

 of bichromate of potash in 70 to 80 per cent, alcohol. 



The bichromate solution is conveniently prepared by mixing 

 one part of a 5 per cent, aqueous solution with about four 

 parts of 80 to 90 per cent, alcohol. The mixture should be 

 made immediately before using, and should be kept from the 

 light (light precipitates it) during the process of decolouration, 

 and should also be changed for fresh several times during the 

 process. After the differentiation of the colour has been accom- 

 plished, the objects should be thoroughly washed (still in the 

 dark) in several changes of 70 per cent, alcohol. 



Preparations made in this manner are more transparent and 

 better preserved than those made by Heidenhain's process. 



For staining celloidin series of sections, Apathy also (Zeit. 

 f. wiss. Mik., vi, 2, 1889, p. 170) recommends the following 

 procedure : Stain in the haematoxylin solution as above for 

 ten minutes; then remove the excess of haematoxylin fluid 

 from the sections by means of blotting-paper, and bring the 

 series for five to ten minutes into 70 per cent, alcohol contain- 

 ing only a few drops of a strong (15 per cent.) solution of 

 bichromate. This must be done in the dark. If the haema- 

 toxylin be not removed with blotting-paper as described, the 

 celloidin will take the stain. The sections should appear steel- 

 blue to steel-grey. 



180. Weigert's Haematoxylin. This method, which is the 

 inverse of Heidenhain's, is, with some unimportant exceptions, 

 only applicable to nerve-tissues, and therefore will be described 

 in the chapter on Nerve Methods in Part II. 



181. Minot's Hsematoxylin Methods (Zeit.f. wiss. Mik., iii, 2, 1886, 

 p. 177). Minot's account of these is as follows : " They may be employed 

 with sections of tissues hardened in various ways, and need not be confined 

 to Miiller's fluid or chromic acid specimens (as in Weigert's process). The 

 sections are soaked first in a salt solution for ten to fifteen minutes. The 



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