' The finer Structures of the Nerve Cells of Invertebrates. 45 



In Figs. 3 and 7, it is to be observed that certain granular rows 

 frequently stain as continuous red and blue lines, in which 

 it is impossible to distinguish the individual granules. 



In iron-haematoxylin preparations, in which the differentiation 

 process has not been carried on to any great extent, the same lines 

 are also to be found. In each instance these lines appear to possess 

 the same structure throughout their length. 



In iron-haematoxylin preparations, they might easily be mistaken 

 for coarse fibrils, were it not for the circumstance that in other pre- 

 parations (methylen blue-eosin, etc), they stain in a manner 

 similar to that of the chromophilous granules, which, 

 as already shown, is different from that of the fibrils. 



So far as my observations go, these so-called granular lines 

 represent instances in which the stain has not been removed from the 

 spaces between the granules arranged in rows. This topic will be 

 considered again in connection with a critique of Rohde's results. 



We now pass to a more detailed account of the topographical 

 arrangement of the granular rows and fibrils in the cell body. 



Many investigators have described a concentric arrangement of 

 fibrils about the nucleus, and especiall for the nerve cells of Gastro- 

 pods. Among these investigators, the name of H. Schultze is most 

 prominent. 



In cells freshly isolated in indifferent fluids, he found the fibrils 

 arranged concentrically about the nucleus, and traced the former back 

 into the axis-cylinder process. In these cells, he also found an ab- 

 sence of granules, but in fixed preparations, granules were most ab- 

 undant between the fibrils, and he concluded that the latter were arte- 

 facts due to the coagulation of a fluid ground -substance in the cell. 



In addition to Schultze, Vignal (43) has described a concentric 

 arrangement of fibrils about the nucleus in the ganglion cells of Gastro- 

 pods. Kohde's figures of Gastropods nerve cells also show a some- 

 what similar arrangement of fine fibrils in the cell body. 



My own investigations on the nerve cells of Gastropods (Helix, 

 Avion and Limax), have led me to the conclusion that a concentric 

 arrangement of fibrils and granular rows is characteristic of many of 

 these cells. 



I say 'many of these cells', because serial sections taken through 

 corresponding planes, do not always show that similarity in the ar- 

 rangement of their fibrils and granular rows, which one might expect 

 to find if an ideal concentric arrangement, as figured by Schutze, 

 were at all times characteristic of all these cells. 



