124 DR. J. Sl'EPHENSOX OX THE JIORPUOLOGY, CLASSIFICATIOX, 



outlines are not visible in it, and there are numerous lightly 

 staining nuclei (w.) ; there are also many yellow granules 

 resembling chloragogen, often aggregated into considerable 

 masses (a-.). Blood-vessels (b.v.) traverse the cavity ; in some 

 cases the chloragogen-like granules are in — and indeed block — 

 the blood-vessels. 



The male funnel is a region of high columnar epithelium (/".) 

 surrounding the exit of the vas deferens from the sac ; the cells 

 are exceptionally high near the opening of the vas, and become 

 lower by degrees at the periphery of the patch ; their nuclei are 

 much elongated, and are placed at or above the middle of the 

 height of the cells. The vas deferens (r. def.) after emerging is 

 attached in numerous closely-set short loops on the posterior side 

 of the septum. 



The testis (i,) is a cellular proliferation just anterior to the 

 opening of the vas deferens ; it is thus implanted actually on the 

 funnel. Its attachment is narrow, but the cell-mass spreads out 

 considerably inside the sac. Near its attachment the nuclei are 

 small, and stain deeply ; in the middle portion of the organ the 

 nuclei are closely packed, with the chromatin in discrete rounded 

 particles ; more peripherally, cell outlines, which are wanting in 

 the more central (or proximal) parts of the testis, appear ; and 

 lastly, discrete cells are detached from the surface of the organ. 

 There were no ripe, or even ripening, spermatozoa in the sacs (the 

 Moniligastridse are apparently characterized by a seasonal sexual 

 maturity, like the Limicola?, and unlike most earthworms ; the 

 clitellum, for example, is often absent or very poorly marked) ; 

 moreover, it is pretty evident that the pinkly staining mass, with 

 small lightly staining nuclei, which fills out the gi'eater part of 

 the sac, is not directly concerned in the formation of spermatozoa. 



(3) The Prostates. 



There already exist a number of observations on the structure 

 of the prostates in the genus Drawicla, but these are not concor- 

 dant throughout. The lining epithelium, the layer of muscular ■ 

 fibres, and the " gland cells " are distinguished in all descriptions; 

 but authors are not agreed as to whether the gland cells are to 

 be referred to the peritoneal or to the epithelial layer. 



Beddard, in a first communication on D. harwelli (2), states 

 that outside the layer of muscular fibi-es there is a layer of pecu- 

 liarly modified peritoneal cells. In a later account (3) this 

 glandular tissue is described as consisting of large granular cells 

 separated into groups by partitions ; each cell is prolonged into a 

 fine process, which extends at least as far as the muscular wall ; 

 indeed, says the author, it is difficult to believe that the cells do 

 not in some way or other reach the lumen of the atrium and 

 there discharge their secretion. Nevertheless, this layer of gland 

 cells is the modified peritoneal layer, and there is no peritoneal 

 coat outside it. 



