The finer Structure of the Nerve Cells of Invertebrates. 29 



RoHDE, it can easily be seen how a part of the nuclear chromatin 

 might be forced into the cell substance, and produce structures similar 

 to those figured by him. 



I have also observed that the nuclear membrane is exceedingly 

 thin, or apparently lacking in certain cells, but in properly preserved 

 material, I have always found the chromatin contained within the 

 confines of the nucleus, and not extending into the cell body. 



Finer Anatomy of tlie Granglion Cells of Helix and Avion, 



Fig. 1 represents a section taken through the supra- oesophageal 

 ganglion of Arion as seen under a low power objective. It shows a 

 portion of a nest of ganglion cells surrounded by their neuroglia capsule. 



The section was fixed in sublimate and stained with methylen 

 blue and eosin. Its most noticeable feature is the different manner 

 in which its several constituent parts are stained. It is seen that the 

 only portions of the section which appear to be stained by the me- 

 thylen blue are the bodies of the ganglion cells and 

 their nucleoli; the latter staining a deep red or purple, 

 while the axis cylinder processes, chromatin granules 

 of the nucleus and the neuroglia tissue, are stained 

 red by the eosin. This differential mode of staining 

 invariably results when sections of ganglion cells, and 

 the neuroglia tissue which envelops them, have been 

 properly stained by this double stain^). 



An examination of Figs. 2, 3 and 4 which represent highly 

 magnified ganglion cells of Arion (2 and 3) and Helix (4), shows that 

 the blue appearance presented by the cell body in Fig. 1, is in reality 

 due to the presence therein of a large number of small bodies 

 having a granular appearance, which stain deeply in 

 methylen blue. It it also to be observed that, between 

 these granules, the substance of the cell is stained red 

 by the eosin. 



These small chromophilous granules, which are alone stained by 

 the methylen blue, are confined chiefly to the body of the 

 cell, but their mode of distribution in the same is 

 variable. 



1) This statement applies equally to the nerve cells of those Crusta- 

 ceans and worms which I have examined. A description of these will, 

 however, be reserved for a future paper. 



