The finer Structure of the Nerve Cells of Invertebrates. 53 



by the same method — a circumstance which serves to decrease the 

 possibility of their being artefacts. 



My results agree with those of v. Lenhossek as well as those of 

 Miss Lewis in that these structures are confined to cells of a 

 certain size and not to all. 



The marked radial arrangement of granules, observed by Miss 

 Lewis, was not to be made out in my preparations, and in this respect 

 my figures agree with v. Lenhossek's. 



The granules surrounding the disks, appeared, in my preparations, 

 to have a diffuse arrangement, and in this respect favor the 

 theory already enlarged on by me, that the chromophilous gra- 

 nules in the cell body are isolated bodies,and not vari- 

 cose thickenings of fibrils. 



One feature in connection with Fig. 21, which serves to show the 

 genuine character of the disk, is the arrangement of the spherical 

 pigment granules arround one of its sides. These pigment granules 

 lie in the granular area just outside the clear space which sur- 

 rounds the disk. Why they would assume this regular arrangement 

 around the disk, unless the latter possesses some controlling 

 force over the outlying granules, is difficult to answer. Also the 

 presence of a clear space surrounding the disk, and the well defined 

 outline of the disk itself are factors which greatly favor the view that 

 these structures are morphologically equivalent to the centrosomes 

 and spheres commonly found in other cells. 



The work necessary for preparing this paper has prevented my 

 giving sufficient time to present here an analysis of Rohde's results, 

 as embodied in his paper "Ganglien zellkern und Neuroglia" (38). 

 I intend, however, in the near future, to give a detailed critique of 

 the same in connection with the structure of the nucleus of the ganglion 

 cells of Helix. 



At present, it is sufficient to say that I have also frequently 

 found bi-nuclear cells in the ganglia of Eelix (Figs. 18 and 19) and 

 also, before Rohde's paper appeared, had noticed in the peripheral 

 region of these ganglia (infra- and supra-oesophageal ganglia of H.elix\ 

 appearances not unlike those represented by his fig. 4 a, tab. 9. I 

 regarded these, however, as not in any way connected with ganglion 

 cells, but rather with an increase of the neuroglia tissue and nuclei. 

 At the same time, I was much impressed with the close resemblance 

 that existed between the nuclei of the smallest ganglion cells, and 

 those of the neuroglia, and think it quite possible to confound the two. 



