342 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



nephridia which is closely allied to that found in higher 

 Oligochaeta and typically in Lumbricus. Yejdovsky (1884) 

 contradicts this, and definitely states that there is no 

 connection between the ventral vessel and the nephridia. 

 I am disposed to agree with Yejdovsky that there are no 

 special branches passing from the ventral vessel to the 

 nephridia, but at the same time we ought not to lose 

 sight of the fact that, as has already been stated, the 

 nephridia are always in close connection with the ventral 

 vessel. This suggests the possibility that the excretory 

 products which collect in the blood during its passage 

 round the body are passed out from it, while in the 

 ventral vessel, to the nephridia, the walls of which are 

 very thin and would form no barrier to the diffusion 

 through them of these waste products. 



Since the nephridium occupies two segments, it 

 follows that the tube must pierce the intervening septum. 

 We may, therefore, divide the whole nephridium into 

 pre-septal and post-septal portions. The pre-septal part 

 consists of the nephrostome, or funnel, and a very short, 

 uncoiled portion of the nephridial tube. By far the 

 greater part of the nephridium, therefore, lies behind 

 the septum, and consists of a much coiled tube which can 

 be divided into certain regions according to the structure 

 of its walls. This tube terminates in the external 

 aperture or nephridiopore, which is situated at the apex 

 of an enlarged vesicle forming the terminal portion of the 

 nephridial tube. It is possible by careful teasing out of 

 part of the intestinal region of the living worm to separate 

 portions, at any rate, of the nephridium. It is extremely 

 difficult, however, to obtain a good view of the nephro- 

 stome and nephridiopore by this means. In some cases 

 the nephridium can be examined in situ if the body wall 

 be sufficiently transparent, and in this way the cilia can 



