TUBIFEX. 369 



duct, and in sections these are all seen to converge 

 towards one point, that point being where the prostate is 

 in communication with the spermiducal gland. At this 

 point, the muscular and peritoneal layers of the wall of 

 the gland are interrupted so that the cells of the prostate 

 and those of the innermost layer of the gland are 

 intimately connected with one another. In fact, it has 

 been said by those observers, e.g., Vejdovsky, who have 

 studied the development of the spermiducal gland and the 

 prostate, that the latter is simply formed as a prolifera- 

 tion of the cells of the lining epithelium of the gland. 



The wall of the spermiducal gland is composed of the 

 following layers: — (a) An inner epithelium, (b) A 

 muscular layer, and (c) Peritoneum. 



Beddard states that the lining epithelium of the 

 spermiducal gland in Limnodrilus is ciliated, and this 

 suggests the possibility that a similar condition obtains 

 in the other members of the family Tubificidae. 

 Vejdovsky certainly believed it to be ciliated in 

 Tubifex, as he states that the prostate is derived from 

 cells of the ciliated lining epithelium. In the mature 

 worm, at any rate, I have never been able to identify cilia 

 in the gland, and as the second portion of the vas deferens 

 is not ciliated this is not surprising. The cells of 

 which this epithelium is composed differ a good deal in 

 structure and appearance at different stages of their 

 development. In a young worm, whose reproductive 

 organs are all developed but not yet matured, the lining 

 epithelium of the spermiducal gland is composed of a 

 single layer of rather low cells, cubical in shape, with 

 oval nuclei which are large and conspicuous and situated 

 near the outer end of the cell. The cell is filled with a 

 dense, granular cytoplasm, which stains deeply with 

 nuclear stains such as borax carmine. Just at the 



