PLATE XVII. 



Fl(; . 71.-Cross section of the nerve of a digital tentacle. Borax carmine and Lyon* blue .tain. The ganglion cells 



Fig. 72.-Ephhdfum of the inner side of an annular ridge of adigital tentacle. Also two isolated epithelial cells 

 from the inner surface of the ridge. ,„, „ , . „„ 



Eta 7o -Section of the secretory epithelium from a gland of Van der Hceven's organ. The secretory cells had sep- 

 " arated from the submucosa, revealing the sensory cells which lie between then,. As the section *as 



somewhat oblique, the outer ends of the cells are not shown. 

 230 ^ 



o 



