14 CHARLES P. W. MCCLURE, 



In connection with my own study of the nerve cells of Inverte- 

 brates, which included numerous examples from the Mollusca, Arthro- 

 poda and Vermes, it was found as recently described by Pflücke (30) 

 for Astacus and Helix^ that the contents of these nerve cells, as in 

 the case of those of Vertebrates, were also divisible into two general 

 classes of elements — stainable and unstainable — by virtue of their 

 relative affinity for methylen blue. 



The writer further observed , when cells had been stained in 

 certain combination stains, that the chromophilous substance stained 

 in a manner so entirely different from that of all other structures 

 (portions of nucleus excepted) within or without the cell (as ground 

 substance, fibrils and neuroglia), that all possibility of confounding it 

 with any of the last mentioned structures was practically eliminated. 



These results, although independently arrived at, were not publish- 

 ed in preliminary form (see 22), until Pflücke's publication had 

 made its appearance. However, by reason of the circumstance that 

 they were obtained by means of methods somewhat different from 

 those used by Pflücke, they will prove, I trust, of some importance 

 in establishing the generality, that a chromophilous substance forms 

 a constituent element of the nerve cells of Invertebrates. 



According to my observations, these chromophilous structures 

 appear as small granules which are arranged chiefly in rows; and 

 the general arrangement of these granular rows, although variable for 

 the cells of different Invertebrates, seems in most cases to correspond 

 to the course of the fibrils within the cell body. This close relation- 

 ship between fibrils and chromophilous structures, has been described 

 by Pflücke as characteristic of the nerve cells of Astacus^ in which 

 he figures these structures, not as isolated granules lying upon or 

 between the fibrils, but as varicose thickenings of the latter. 



The question concerning the real nature of these chromophilous 

 structures, that is, whether they are isolated structures and represent 

 granules in the strict sense of the word, or whether they are merely 

 thickenings of fibrils, is in many cases difficult to decide exactly; 

 however, so far as my observations are concerned, the balance of 

 evidence at the present writing, seems to be in favor of the former 

 view. 



The presence of granules in the nerve cells of Invertebrates is 

 by no means a new idea. They have been frequently described in 

 the past as representing normal constituents of the cell, or as "arte- 

 facts" produced in the same, by the coagulation of the cell substance. 



