50 KARM NARAYAN BAHL 



The essential feature of this system is that the numerous septal 

 and pharyngeal nephridia (all micronephridia) are connected 

 with an elaborate system of ducts, which open, not on the 

 surface of the skin but into the lumen of the intestine and other 

 regions of the gut (buccal cavity and pharynx). These nephridia 

 of the ' enteronephric ' type co-exist in Pheretima with 

 the integumentary nephridia, which are exceedingly numerous 

 on the inside of the body-wall, and open on the surface of 

 the skin through separate nephridiopores, like ordinary 

 Oligochaete nephridia. Although in my paper I referred very 

 briefly to the possible physiological significance of the discharge 

 of excretory fluid into the gut of this worm, I did not enter, 

 for want of embryological data, upon any discussion concerning 

 the morphological significance of the discovery of the ' entero- 

 nephric ' type of nephridial system, in relation to the com- 

 monly accepted view, due mainly to Goodrich (9 and 10), 

 that all Oligochaete nephridia ' develop centripetally as it 

 were, and quite independently of the coelom and are probably 

 derived from the epiblast '. 



While little doubt could be entertained, from a study of 

 the disposition of the nephridial system of the adult worm, 

 with regard to the ectodermal origin of the integumentary 

 nephridia, it was difticult to believe that the septal and pharyn- 

 geal nephridia also had a similar origin for two reasons. In 

 the first place, these nephridia have not only no connexion 

 with the body-wall but are connected instead with the inter- 

 segmental septa, which are mesodermal structures ; and they 

 open, through an elaborate system of ducts, presumably 

 mesodermal, into the lumen of the gut, the wall of which is 

 partly mesodermal and partly endodermal. In the second place, 

 the septal nephridia differ from the integumentary ones in 

 that the former possess open ' funnels ', which are absent in 

 the latter. Although no solenocytes or ' flame-cells ' have been 

 found on the integumentary nephridia, the presence of a 

 coelomic funnel in one case and its absence in the other might 

 lead one to ascribe a different origin to the two sets of structures. 

 In fact the connexions of the septal nephridia and their ducts 



