314 ME. H. H. STIRRUP ON 



with the gut has been known for some time, but it has never 

 been satisfactorily explained why this is so. My own observations 

 show that spermatozoa are occasionally seen in the tube con- 

 necting the ampulla with the gut, but by far the majority ai-e 

 stored in the ampulla with their heads buried in the wall and 

 their tails free in the cavity of the ampulla. In transverse 

 sections, at the point where the spermatheca opens into the gut, 

 I have occasionally seen a number of spermatozoa actually in 

 the gut. Although they were quite near to the spermathecal 

 opening, I think this observation supports the view that this 

 connection between spermatheca and gut has some definite 

 function, probably to allow the excess spermatozoa to escape from 

 the spermatheca. 



One can always see where the gut ends and the spermatheca 

 begins, because the epithelial cells of the gut are ciliated, whilst 

 those of the spermatheca are not. 



Some time ago I had the good fortune to observe two Enchy- 

 trseids in copulation. They were lying quite still, with the 

 ventral surfaces very close together, so that the spermathecal 

 opening in each worm was directly in touch with the male 

 opening of the other worm. They were so tightly fixed together 

 that even whilst killing and fixing them they did not separate, 

 and so I was able to obtain sections through this region. Fig. 17 

 (PI. XLVIII.) shows a drawing of the ventral clitellar region. 

 From this it is seen that there is a shallow depression, overhung 

 on each side by a lip. Underneath each lip and in the groove 

 is the male opening. During copulation the fifth segment of 

 one worm fits closely into this shallow depression and is held in 

 position partly by the overhanging lip, but also probably by the 

 secretion of certain glands in this region, to be described later. 

 Fig. 19 (PI. XLIX.) shows a drawing of a section through these 

 two copulating Enchytrseids. The ampulla of the spei'matheca 

 is seen on one side, whilst on the other side is the external 

 opening of the other spermatheca in close approximation with 

 the penis-like termination of the sperm-duct, which is protruding 

 through the male opening. 



Sperm-funnels. — The sperm-funnels of E. pellucidus occupy 

 the clitellar region. They are very long, sometimes being as 

 much as seven or eight times as long as broad, and are often 

 bent upon themselves. They lie free in the body-cavity. The 

 mouth of the sperm-funnel is large and has a swollen ridge, 

 in which are embedded the heads of numerous spermatozoa. 

 The tails of the spermatozoa hang out stiff and straight like 

 the bristles of a brush, and when viewed in the living worm 

 are of a beautiful golden-brown colour. The sperm-duct leads 

 from the sperm-funnel and is very long and coiled. It is very 

 strongly ciliated internally along the whole of its length. The 

 coils of this sperm-duct are free in the body-cavity and often 

 extend a dozen segments behind the clitellum before finally 

 ending in the male opening on segment 12. 



