40 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 



from which the drawing was made into irregular wavy strands which 

 are in all probability largely the result of preservation, but are in part 

 also due to the separation by processes of the epithelial cells, as was seen 

 in Fig. 47. The axis is seen with one of its longitudinally directed bipolar 

 ganglion cells ; and at the sides the fibres of the circular muscle of the 

 subumbrella. These show a slanting direction to the nerve, due to the 

 fact that the nerve, as mentioned before, has a sinuous course from the 

 margin in interradius to the level of sensory club in perradius. At the 

 next focus (4) we come to the gelatine of the subumbrella (gs in Fig. 47), 

 and below this (5) to the larger polygonal outlines of the endodermal 

 cells of the stomach pocket (enp, Fig. 47), which like the ectoderm show 

 mucous cells at irregular intervals. 



A comparison, now, with Claus's figures ('78, Taf. II, Figs. 19-21) will 

 show that, except for the rather unimportant matter of the mucous cells, 

 which he finds regularly and thickly disposed on each side of the nerve 

 ('78, Fig. 21), our only .essential difference lies in the matter of sensory 

 cells in the epithelium. His figures show a multitude of spindle-shaped 

 sensory cells whose central ends are continued in processes that bend 

 around into the mass of fibres of the nerve. In his Fig. 20 a relatively 

 small number of nuclei, j ust one-third as many, are seen attached nearer 

 to the surface, which represent the supporting cells. The plan of struc- 

 ture (as shown in his Fig. 20) is an alternation of (1) supporting cells 

 offering a broad peripheral end to the surface and having the central end 

 continued as a supporting fibre to the gelatinous lamella, and (2) spindle- 

 shaped sensory cells with nuclei at a lower level, which send their 

 peripheral process up between the supporting cells to the surface, while 

 the central process becomes continuous with the nerve fibres, often 

 branching into two processes. In my sections I have not been able to 

 see either a regular alternation of nuclei at different levels, or central 

 processes which unmistakably bend round into the nerve fibres. In 

 every case in which I could trace the central process of a cell clearly it 

 ran to the supporting lamella, and this whether the nucleus of the cell 

 lay near the surface of the nerve or deeper down, as in the somewhat 

 spindle-shaped cell seen on the left of the centre of the nerve in Fig. 47. 

 Of course in many cases the central process could not be traced in a 

 section, and this leaves room for the supposition that such were always 

 the sensory cells. From my inability to demonstrate sensory cells in the 

 nerves of Charybdea, I by no means wish to deny their existence ; for 

 that remains to be proved, or disproved, by macerations. At any rate, 



