80 KAKM NARAYAN BAHL 



could be traced further to the original nephric row derived 

 from the ectoderm. This group of cells pushing its way into 

 the septum forms the primitive material foundation of all the 

 septal nephridia. The primary pair is formed from one of the 

 cells of this group, travelling dorsally on each side. More cells 

 move into the septa and give rise to the other nephridia 

 (secondary septals). That this does actually happen is shown 

 firstly by the fact that there are always a number of cells lying 

 into the septum at its junction with the body-wall, even after 

 the rudiments of the primary pair of nephridia are well formed 

 dorsally ; and, secondly, by the fact that we very often come 

 across cells lying interperitoneally within the septa at a little 

 distance dorsal and inwards to the group of cells referred to 

 above (the group pushing its way into the septum), these cells 

 having apparently been detached from the fundamental group 

 and being on their way to their final place of settlement and 

 growth. 



We thus conclude that although the secondary septal 

 nephridia do not originate as buds from the primary ones and 

 are completely independent of them as regards their origin, 

 they can be traced to the same source as the primary nephridia, 

 i. e. the intersegmental group of nephridial cells, which form 

 a store-house, giving origin to the rudiments of all the septal 

 nephridia, primary as well as secondary. 



Coming now to the later development of the secondary 

 nephridia, the chief point of interest is the topographical 

 position of the funnel. The usual position of the funnel is 

 always pre-septal, and we have seen that it is so with regard 

 to the funnels of the primary pair of septal nephridia. But 

 in the adult Pheretima (1) I have described the funnel 

 as lying in the same segment as the rest of the nephridium, 

 and there was thus an incongruity between the two facts of 

 structure. This led me to a close examination of the fmmels 

 of the developing nephridia in the embryos, and also to a 

 re-examination of the position of the fumiel in the adult worm. 

 While, on the one hand, it came out that all the primary 

 nephridia have a pre-septal fumiel, in the secondary nephridia, 



