444 MYELIN STAINS. 



several hours), and are then well washed with water (running, or 

 changed several times), dehydrated, and mounted in balsam. They 

 may be previously counterstained, if desired, with alum-carmine. 



The method is applicable to the study of peripheral nerves as 

 well as to nerve centres, and also the study of lymphatic glands, 

 skin (see SCHIEFFERDECKER, Anat. Anz., ii, 1887, p. 680), bile 

 capillaries, and other objects. 



The process is applicable to tissues that have been hardened in 

 alcohol or in any other way, provided that they be put into a solution 

 of a chromic salt until they become brown before mordanting them in 

 the copper solution. 



It is not necessary that the mordanting be done in bulk. MAX 

 FLESCH (Ztschr. wiss. Mikr., iii, 1886, p. 50) prefers (following LICH- 

 THEIM) to make the sections first, and to mordant them separately. 

 VASSALE (Rw. sperim. Frematr.,xv, 1889, p. 102) first stains the 

 sections in 1 per cent. ha3matoxylin for three to five minutes, 

 then puts them for three to five minutes into saturated solution 

 of copper acetate, and differentiates as Weigert. 



855. WEIGERT'S 1891 Method (Deutsche med. Wochenschr., xvii, 

 1891, p. 1184). The material is hardened in bichromate and 

 embedded in celloidin (see last ). It is then (according to the latest 

 form of the process (Enzyd. mik. Technik., 1903, p. 942) ), put for 

 twenty-four hours in a stove into a solution of 2 \ parts of chromium 

 fluoride, 5 of copper acetate, and 5 of acetic acid in 100 of water.* 



Sections are then made and stained for from four to twenty- 

 four hours at room temperature in a freshly prepared mixture 

 of 9 volumes of (A), a mixture of 7 c.c. of saturated aqueous solution 

 of lithium carbonate with 93 c.c. of water, and 1 volume of (B), a 

 solution of 1 grm. of haematoxylin in 10 c.c. of alcohol (A and B may 

 be kept in stock, but A must not be too old). The sections should 

 be loose ones, and not thicker than 25 //. They are then washed in 

 several changes of water, and treated with 90 per cent, alcohol, 

 followed by carbol-xylol, or by a mixture of 2 parts of anilin oil with 

 1 of xylol, then pure xylol and xylol balsam (not chloroform balsam). 



It was, however, found that preparations thus made, without 

 differentiation, did not keep well, and WEIGERT (Ergebn. Anat., iii, 

 1894, p. 21) reverted to the practice of differentiating with the 

 borax-ferricyanide mixture. 



* Instead of the chromium fluoride one may use chrome alum, as 

 Weigert did at one time, and as some still do. But then one must boil, 

 as directed for Weigert's Neuroglia stain. 



