CHAPTER XL 



NERVOUS SYSTEM— SPECIAL METHODS CHIEFLY 



CYTOLOGICAL * 



A. METHODS FOR CELLS, DEMONSTRATING TIGROID SUB- 

 STANCE AND OTHER GRANULAR MATERIALS 



1000. Tigroid substance or bodies, chromophilic or chromato- 

 philic substance or material or granules, Nissl's bodies or granules, 

 etc., are all denominations for a markedly basophil substance 

 which appears as blocks, granules or irregular patches within 

 the cytoplasm of nerve-cells under certain conditions of fixing 

 and staining. 



It is now universally admitted that this substance exists in 

 the living cells as a fluid or semi-fluid " plasm rich in nutritive 

 value," and that the blocks, granules or patches are appearances 

 chiefly due to the coagulation of this plasm, as brought about 

 by the fixing agents employed for their demonstration. As, 

 however, these bodies or granules appear always the same under 

 constant optical conditions in healthy cells fixed and stained 

 in a constant manner, they are said to be the equivalent of such 

 healthy cells during life. " It follows that if the cells, prepared 

 by the same method and examined under the same conditions, 

 show a difference from the equivalent or symbol of healthy cells, 

 the difference is the measure of some change that has occurred 

 during life." (Halliburton, " Handbook of Physiology," London, 

 1920, p. 194. See also Einarson (Am. Journ. Path., viii, 1932, 

 295).) 



This is pointed out to make it quite clear why Nissl has always 

 insisted that his method should be carried out according to 

 his suggestions, and in a constant manner. At first {Neurol. 

 Centralb., iv, 1885, p. 500) he used to stain sections of material 

 fixed in alcohol with a warmed v/atery solution of magenta or 

 dahlia violet or vesuvine, and to differentiate them with alcohol. 

 Later (Allg. Ztschr. Psych., xlviii, 1892, p. 197) he suggested 

 floating sections on a warmed solution of methylen blue (B 

 patent), with subsequent differentiation with a 10 per cent, 

 solution of anilin oil in 96 per cent, alcohol. The present form 

 of the method was published in 1894 (Neurol. Centralb., xiii, 

 p. 507) ; but Nissl continued to introduce into it slight modifi- 



* Revised by J. G. G. and R. O. S. 



' 468 



