PLATE XVII. 



Kra. 71. — C'rosa section of the nerve ni a difjitai tentacle, liorax cai'niin<' ami Lyons bine stain. The ganglion cells 



in red. 

 Fig. 72. — Epithelinni of the inner side of an annular ridge c.f a di<_'ital tentacle. ,\lso two isolated epithelial cells 



from the inner surface of the ridge. 

 Fig. 73. — Section of the secretor}' epithelinni from a glan<l of Van der Hceven's (irgan. The secretory cells had sep- 

 arated from the snbmucosa, revealing the sensory cells which lie between them. As the section was 

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

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