540 H. LYSTEE JAMESON, 



a rich ganglionic supply to the skin in an animal of so sluggish habits 

 would be difficult to imagine. 



The protoplasm of these "Fadenzellen" appears striated under 

 high magnification. This is due to the arrangement of the alveoli 

 in rows perpendicular to the cuticle in the distal parts of the cells. 

 The nuclei (ep.n) vary considerably in position in ditferent parts of 

 the body, and in different cells; they lie, however, most usually 

 somewhat nearer to the basal ends of the cells. They are ovate or 

 fusiform and contain one or more deeply staining refractive bodies. 

 They stain more lightly than those of the great gland cells, but more 

 deeply than those of the clear cells. On the ventral surface of the 

 proboscis these "Fadenzellen" are ciliated. 



2) The clear cells (Figs. 1, 2, 5 and 6 c.c) which lie between the 

 "Fadenzellen" are shorter than the latter, and occupy the spaces between 

 their outer ends, the root-like basal processes of the "Fadenzellen" 

 separating them from the underlying tissues. Many of them open 

 out through pores in the cuticle, which leads me to believe that they are 

 glandular in nature. Possibly they may have some relation to the great 

 unicellular glands. I cannot always determine the presence of a pore, 

 but when such a structure is not present the cuticle is often thinner 

 over the cell than elsewhere. They are of oval or pear-shaped outline in 

 longitudinal section, the narrower end being directed outwards, i. e. 

 towards the cuticle. Their contents are hyaline, not staining deeply, 

 and chiefly restricted to the inner ends where the nucleus lies {c.n). 

 The nuclei are generally larger and not so deeply staining as those 

 of the "Fadenzellen". On the proboscis these clear cells are very 

 much shorter than the "Fadenzellen" and lie more regularly between 

 them. Their basal ends lie as a rule more in the same plane than in 

 the body integument and these facts, coupled with the presence of 

 muscle fibres between the basal ends of the Fadenzelleu, first found 

 by RiETSCH in BonelUa and observed by me in Thalassema, not un- 

 frequently gives the appearance of a kind of basal membrane which 

 however does not exist. As to the nature of these clear cells I am by 

 no means certain. The frequent presence of an external opening leads 

 me to think that they are of a glandular nature. They are not un- 

 like the clear cells in the epidermis of the male of BonelUa described 

 by Spengel (16, p. 400, 401, tab. 12), and suggest also the "Plasma- 

 zellen" of Capitellidae. Such cells are not uncommon in the epidermis 

 of worms, as a reference to the histological literature of the group 

 has convinced me. The gland cells in the epidermis of Opliryotrocha 

 puerilis described by Korschelt (10) are suggestive of such a 



