46 CHARLES F. W. MC CLURE, 



This apparent discrepancy may be explained on the grounds that 

 it is practically impossible to cut two series of sections in exactly 

 the same plane. Such being the case, it is quite evident that fine 

 structures, like fibrils, may present a very different appearance, so 

 far as their apparent arrangement is concerned in different series of 

 sections. 



On the other hand, this discrepancy may be due to the circum- 

 stance, that the fibrils and granules are constantly changing their 

 relative positions in the cell body, in correlation with changes in the 

 functional activity of the cell. 



A similar discrepancy, in the arrangement of fibrils in the cell 

 body, has also been mentioned by H aller (13) i) for the nerve cells 

 of Invertebrates, in explanation of which he ascribes this last cause. 



Fig. 11, which is a section of a nerve cell from an infra-oeso- 

 phageal ganglion of Helix (FLEMMiNG-iron-alum-haem.), clearly shows 

 a marked concentric arrangement of fine fibrils and granular rows, at 

 the axis-cylinder pole of the cell and in the cell body at either side 

 of the nucleus. 



The fibrils and granular rows are seen to run chiefly in wavy 

 lines, the length of which is exceedingly variable. In many instances, 

 the fibrils and granular rows appear to overlap and run into each 

 other, but no indication of a network arrangement is 

 visible 2). The ectoplasmatic area, on the left side of the figure, 

 is seen to contain fibrils free of granules, and at various points in 

 the granular area, free fibrils may also be seen. In addition to the con- 

 centrically arranged fibrils and granular rows, one frequently meets 

 with these structures running at angles to the concentric plane. Such 

 an arrangement, however, is not plainly seen in the above mentioned 

 figure. 



One other feature to be noticed in connection with the above 

 figure, is the circumstance that the fibrils of the cell body seem to be 

 continuous with those in the axis-cylinder process. 



In Figs. 12 and 13, which are ganglion cells of Helix prepared 

 in the same manner as the section represented by Fig. 11, a con- 

 centric arrangement of fibrils and granular rows is likewise seen. 

 These fibrils and granular rows, however, appear to be more winding 



1) See under "Literature". 



2) It may be mentioned here, that I have never found the slightest 

 indications of a network arrangement of fibrils in any of these Gastro- 

 pod nerve cells. 



