CHAPTER XXXI. 



NEUROLOGICAL METHODS NERVE-FIBRE STAINS (WEIGERT 



AND OTHERS). 



a. Myelin Stains. 



709 Introduction. The most important of the methods for 

 the study of tracts of medullated nerve -fibres are the haema- 

 toxvlin methods of WEIGERT. 



/ 



There have been in all three methods of WEIGERT ; the 

 1884 method, the 1885 method, and tlie 1891 method. The 

 ordinary methods of staining with haematoxylin depend on 

 the employment of an aluminium lake of haematoxylin. 

 WEIGH; RT'S method depends on the formation of another lake, 

 a chromium or copper lake. In consequence of the forma- 

 tion of these lakes haematoxylin acquires the property of 

 staining the myelin of nerves in a quite specific way. 



In WEIGERT'S process the formation of these lakes takes 

 place in the tissue itself. The details of the process have 

 been considerably modified, both by other workers and by 

 WEIGERT himself. The 1884 method (Fortschr. d. Aled., 1884, 

 pp. 113, 190; Zeit.f. wins. Mik., 1884, pp. 290, 564), which 

 depends on the formation of a chrome lake, may be considered 

 to be superseded. Not so the two others, which depend 011 

 the formation of a copper lake. 



For a critical history of these methods, see WEIGERT, in 

 Ergebnisse der Anatomie, vi, 1896 (1897), p. 5. 



710. WKIGKKT'S 1885 Method (Fnrtwltr. <l. Med., 1885, p. 

 136; Zeit.f. u-iss. Mik., 1885, pp. 399, 484; Eryelniase der 

 Anatomie, vi, 1896 [1897], p. 10). The tissues are to be 

 hardened in bichromate of potash. WEIGERT takes (Ergeb- 

 nisse, p. 10) a 5 per cent, solution, and if time is an object 



