90 KARM NARAYAN BAHL 



adult. Bourne (8) found a similar condition in Mahbenus, 

 the funnel, however, in this case degenerating entirely. 



It is easy to derive the condition in Pheretima from 

 what takes place inMegascolides. In the latter the funnel, 

 with part of the tube following it, develops into the large paired 

 nephridium with funnel, a pair to each segment, while the 

 body of the nephridium gives rise to a network of minute 

 excretory tubules. In Pheretima the separation of the 

 funnel from the body of the nephridium is carried a little 

 farther and takes place early in ontogeny. The result is 

 essentially the same as in Megascolides,i. e. the formation 

 of two kinds of nephridia : in this case the larger septal 

 nephridia with funnels and the smaller integumentary ones 

 without funnels. The evolution has taken place along the 

 same lines in Octoch actus and Mahbenus also, but in 

 these two genera the degeneration and disappearance of the 

 portion following the funnel has likewise affected the funnel 

 which also degenerates, and that is why we get only one type 

 of nephridium without funnel in these two cases, although 

 Beddard found some nephridia with funnels towards the 

 posterior end of Octochaetus, along with those without 

 funnels. 



In Pheretima the ' funnel-cell ' along with some other 

 nephridial cells separate off early from the main nephridial 

 mass, and while the integumentary nephridia develop at once 

 from the main nephridial mass the development of the septal 

 ones from the ' funnel-cell ' comes a little later. We tacitly 

 assume, of course, that the ' funnel-cell ' itself by division is 

 capable of giving rise to the whole nephridium, and this is 

 what actually takes place (cf. figs. 13 and 14). Why the funnel 

 gets separated off from the main body of the nephridium dm-ing 

 development in Octochaetus and Mahbenus, and why 

 the separation begins so early in Pheretima — whether it 

 took place in phylogeny before or after the septal nephridia 

 had acquired their openings into the gut — are questions 

 difficult to answer. 



How does this ' funnel-cell ' travel dorsalwards and take up 



