66 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 
cells. Yet, that they pass to the supporting lamella, just as Conant 
shows in Fig. 13, would seem to indicate that they are fibers from 
the supporting lamella or processes of the epithelial cells. While this 
stands as an objection to their being sensory fibers, yet I cannot 
explain away their being continued distally as a flagellum, except I 
assume this continuation to be an artefact. This does not seem 
probable. Perhaps they serve both purposes; namely, that the cell 
body with its axial fiber is continued to the supporting lamella, the 
cell proper ending there, while the axial fiber is continued as a nerve 
fiber. I believe this to be the proper explanation. 
The epithelium of the peduncle is quite like the epithelium of the 
club just described. Sections through the tips of the epithelial cells 
of the peduncle and also sections sagittal to the axis of these cells 
give sections like Figs. 25 and 26. I, therefore, conclude that this 
epithelium is a sensory flagellate epithelium like that of the clubs. 
Nerve tissue and unstriped muscle fibers underly the epithelium of 
the peduncles. Claus and Conant also describe a small ventral endo- 
dermal tract of nerve tissue, which according to Conant is connected 
with the endodermal nerve tissue found in the region of the radial 
ganglia. 
To sum up, the epithelium of the club and the peduncle is a 
flagellate sensory epithelium whose flagella are continued through 
the cells as nerve fibers into the nerve tissue below. <A priori, 
judging from the mass of nerve tissue underlying the epithelium, 
we should expect the epithelium to be one strictly sensory. What 
sense it serves is difficult to surmise. In the physiological part of 
this paper I suggested that it might be tactile, serving in connection 
with the lithocysts in giving the animal sensations of space relations. 
Claus mentions having seen patches of flagella on the epithelium 
of the clubs. Schewiakoff supposes that his spindle-shaped sensory 
cells have only a single flagellum, while his supporting cells have 
many cilia. In the latter supposition he was evidently mistaken. 
Conant (from an unpublished note) saw the flagella of the epithelium 
on the living object and does not think that there could be more 
than a single one to each cell. He also concludes from living speci- 
mens squeezed out under a cover-glass, that there is only one kind 
of cells in the ectoderm. 
Cilia and flagella extending into the cells to which they are 
attached are described by a number of observers. 
