80 ALICE L. EMBLETON ON THE STEUCTURE AND 



Though on the whole, as is seen, the structure of the body-wall in this Japanese 

 species is largely identical with the descriptions given for allied types, yet in one 

 important point this EcJdurus differs from others in the group, for it possesses not only 

 unicellular glands but also large compound glands. These occur in immense numbers 

 but are strictly local in their distribution, being restricted to a wide belt in the anterior 

 half of the animal, coincident with the position of the segmental organs. They are very 

 conspicuous, being the most significant structures in sections of the body-wall, whether 

 they be taken in a transverse or longitudinal direction. As PI. 7. figs. 6, 7 ig.) show, 

 these glands are flask-shaped bodies, built up by radially grouped gland-cells {g.c) with 

 delicate walls ; the secretion (*.) from each component cell is poured into the main duct,' 

 which is lined by the cuticle. The nuclei (iic.) of the gland-cells collect at the basal 

 ends, and, being large, they make a sharp outline of the flask-like character of the whole 

 ,organ (PL 7. figs. 6, 7). These glands are large and sink far down into the cutis (or 

 connective-tissue strata) {t.c), occasionally coming into contact Avith the outer circular 

 muscle-sheath (m.c). Invariably the ducts of these glands discharge on the summit of 

 a papilla ; and, seeing they are found in no other portion of the skin except near the 

 ■segmental organs, it is not improbable that their secretion has some function to perform 

 in connection with the ripe eggs, which pass out by the segmental organs. Or, again, 

 the secretion may be used to form a lining to tlie burrows and tunnels in which the 

 creatures pass their lives. This can only be decided by carefully watching living 

 specimens. Sections of the body-wall of E. PallasU, specimens of which came from 

 St. Andrews, showed however, in the region of the segmental organs, where the 

 compound glands are located in E. unicinctus, only unicellular glands. Tliey were 

 similar to those in other parts of the body, being much modified, as Spengel noted, and 

 having each a long tapering neck, attached to an expanded body embedded in the cutis ; 

 on the proboscis they were larger than elsewhere, but in no region were there any 

 compound glands such as occvir in this Japanese species. 



The cutis is beneath the epidermis ; it consists of connective-tissue brandling cells, 

 with nuclei scattered irregularly throughout. As in all the other layers of the body- 

 wall, no blood-capillaries can be detected (PI. 7. figs. 6, 7, 8, 9, 10, i.e.). 



The muscle-sheath comes next ; the outermost layer is made up of circularly arranged 

 fibres; below this is a band of longitudinal muscles, followed on the inner side by 

 another layer of circular muscles, showing, however, a slight obliquity as compared with 

 the outer circvilar layer {m.c). 



Sections cut in different parts of the body show all these parts in very varying 

 proportion. Median sections exhibit but feeble papillation, and the unicellular glands 

 are more scattered, while the large compound glands are absent altogether ; the cutis 

 and muscle are also proportionately reduced (PL 7. fig. 8). A great difference is 

 observable in sections taken through the thickened wall of the jwsterior end (figs. 9, 10), 

 the immense increase in depth being mainly due to a development of longitudinal 

 muscles ; the papillae are striking, but possess no compound glands. 



It is difficult to discover how far the epidermis of the body-wall extends at the 

 posterior extremity of this worm, for there is no definite line of demarcation showing 



