The finer Structure of the Nerve Cells of Invertebrates. 35 



cylinder process, in which the difference in the staining capacity of 

 these two regions is clearly shown. 



The reason for this difference in the staining capacity of these 

 two regions, is seen to be due to the exclusive presence in the 

 cell body of certain particles having a granular ap- 

 pearance which possess a marked affinity for the dye^). 



These FLEMMiNG-iron-haematoxylin preparations are particularly 

 interesting for the reason that they show with great clearness, not 

 only the small chromophilous granules, which have formed the chief 

 topic of inquiry in the preceding pages, but also certain spindle- 

 shaped structures in the cell body, which in all pro- 

 bability are collections of small chromophilous gra- 

 nules 2) (see Figs. 10, 11, 12 and 13). 



An examination of the last mentioned figures (FLEMMiNG-iron- 

 haematoxylin), shows that the small chromophilous granules stain more 

 deeply than any structures in the axis-cylinder process, that they are 

 found exclusively in the cell body, are smaller than the deeply stained 

 spindles, and considerably larger than what would be the diameter 

 of a transverse section of an axis- cylinder fibril. These facts, together 

 with the circumstance that they agree in size, form and mode of 

 distribution with the chromophilous granules already described in 

 connection with cells fixed in sublimate and stained by double stains 

 (methylen blue-eosin, etc.), seem sufficient evidence to prove that they 

 are in no sense artefacts, but rather constant and definite structures 

 in these nerve cells. 



For further proof of the genuine character of these small chromo- 



1) Although the interpretation of the cause which produces it may 

 differ from that ascribed by me, many authors have also figured, for 

 the nerve cells of Invertebrates, a similar differentiation of the cell 

 contents into a deeply stained cell body, and a lightly stained process. 



See Rawitz (31, tab. 24 and 25), Nansen (25, tab. 4, figs. 37 and 

 38), RoHDE (37, tab. 24, fig. 1), Binet (1, tab. 12, figs. 3 and 10), and 

 also Pflücke's (30) figures. I regard the cause which produces this 

 difference in all of the cells, to be due to the presence in the cell body 

 of chromophilous granules. 



2) In the preliminary paper, which I recently published on this 

 subject, and which contained the chief features embodied in the present 

 paper, it was suggested as a possibility that the "spindles" might be 

 nothing more or less than collections of smaller granules. After a more 

 extended investigation of this subject, I have come to the conclusion 

 that this is undoubtedly the case. 



3* 



