BY VERA A. IRWIN-SMITH. 777 



but easily recognisable walls and loose, granulated protoplasm. 

 Kach cell contains a large, oval nucleus, having a single, more 

 darkly staining nucleus in it. There are from six to eight cells 

 in cross-section. Further back, the entire canal becomes crushed 

 up against the dorsal body- wall by the growth of the genital 

 organs, and the walls become thinner (Text-figs. 12, 13, 20-22, (^.). 

 Behind the genital pore, where it passes backward to the left of 

 the posterior ovary, its walls are very thin, and the cell-bound- 

 aries and nuclei are difficult to distinguish, w^hile the protoplasmic 

 contents become denser(Text-figs. 23-24, oe..). Vacuoles(Fig.24,'y.) 

 and numerous rounded bodies, staining deeply pink with eosin, 

 are present. 



Immediately behind the posterior ovary, at the level where 

 the first setae of the ventral rows appear, it completely fills up 

 the coelomic cavity (Text-figs. 1 2, 14, \b^int.). Here, the walls 

 are still thin, so that the lumen is relatively very large, and this 

 part of the canal may, perhaps, be regarded as a stomach. The 

 walls increase in thickness as it passes back, though still formed of 

 a single layer of from 15-20 cells, which vary considerably in size. 

 A short distance in front of the anal aperture, it passes suddenly 

 into the rectum through a narrow passage surrounded by eight 

 or nine very large, wedge-shaped cells with clear, protoplasmic 

 contents, and large, round nuclei (Text-fig. 16, a;.). Behind the 

 constriction, the walls are extremely thin (Text-fig. 17, re), the 

 passage is dorso-ventrally compressed, and lined with cuticle, 

 and the anus, by which it opens on the ventral surface, is a 

 transverse slit situated on a slight projection. A good deal of 

 food-matter is present in all parts of the enteric canal in the 

 adult worm, but it consists of a kind of granular debria, in which 

 it is difficult to recognise anything definite. I have seen, how- 

 ever, a Desmid, a small Foraminiferal shell, and several chains 

 of minute Algal cells among the debris. In an immature female 

 worm, the cells forming the wall of the enteric canal are rela- 

 tively very large, and few in number; and the lumen is very 

 small, in parts almost completely closed-up (Text-figs. 6-8). Sur- 

 rounding the anterior end of the pharynx, there is a group of 

 large cells staining deeply blue with hsematoxylin, which pro- 



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