426 APPENDIX. 



c. Transfer to 80 per cent, alcohol y z -\ hour. 



d. Cut sections ; knife and tissue wet with 80 per cent, alcohol. 

 The later method of Weigert directs the preparation of the fol- 

 lowing staining solutions : 



A / Lithium carbonate (1.2 gm. : ioo c.c. HsO) 7 c.c. 



( Distilled water 100 c.c. 



B f Haematoxylin, crystals i gm. 



1 Absolute alcohol 10 c.c. 



e. Stain sections for 12 to 24 hours in mixture composed of 9 

 volumes of A -j- i volume of B. 



f. Wash thoroughly in distilled water. 



g. Transfer to 90 per cent. 15 minutes. 

 h. Transfer to 95 per cent. 15 minutes. 



i. Transfer to anilin oil-xylol (anilin oil 2 vol. + xylol i vol.) 5 

 minutes. 



j . Transfer to pure xylol 5 minutes. 



k. Mount in balsam. 



The exact degree of color must be determined by experience and 

 the individual taste of the worker ; the Weigert method in any of 

 its forms is a stain particularly for the medullated nerve-fibres, the 

 cellular elements being better displayed by carmine or other haema- 

 toxylin dyes. 



Golgi's silver method for displaying the nerve-cells of the cen- 

 tral nervous system has attracted much attention during the last few 

 years, and has very materially extended our knowledge of the rela- 

 tions of these elements. The method is one of impregnation and 

 subsequent reduction, and, unfortunately, in addition to being un- 

 certain, yields preparations prone to change. As it at present plays 

 a conspicuous rdle in the investigation of important organs, it is here 

 given as now suggested by Golgi, the method as used by Ram6n y 

 Cajal being slightly modified. 



a. Harden very small pieces of the tissues in 



Solution of potassium bichromate (2 per cent.) 80 c.c. 



Solution of osmic acid ( i per cent.) 10 c.c. 



b. Transfer directly to 



Silver nitrate .75 gm. 



Water, distilled 100 c.c. 



for 24 hours. 



c. Transfer to 95 per cent, alcohol 12-24 hours. 



d. Cut sections. 



