454 Genital Ducts and Nephridia in the Oligochceta. [Nov. 27, 



of Jfjolosoma has come into my hands ; it appears that in this Annelid 

 there are no special sperm ducts, but that the function of such ducts 

 is performed by several pairs of nephridia. This fact, however, 

 interesting though it is, is not a proof of the homology between sperm, 

 ducts and nephridia in other types. 



I have lately had the opportunity of studying the development of 

 the New Zealand species Acanthodrilus multiporus. The sum of 

 money which the Government Grant Committee of the Royal Society 

 were good enough to place at my disposal has enabled me to defray 

 the expenses of this investigation. 



In the young embryos of this worm eaeh segment is furnished with 

 a pair of nephridia, each opening by a ciliated funnel into the segment 

 in front of that which carries the dorsa'.ly placed external pore. In 

 later stages the funnels degenerate, and that portion of the tube 

 which immediately follows the funnel becomes solid, losing its lumen ; 

 at the same time the nephridium branches, and communicates with 

 the exterior by numerous pores. At a comparatively early stage, four 

 pairs of gonads are developed in segments X XIII ; each of these is 

 situated on the posterior wall of its segment, as in Acanthodrilus 

 annectens, and iaot on the anterior wall, as in the majority of Earth- 

 worms. When the gonads first appear, the nephridial funnels, with 

 which they are in close contact, are still ciliated, and their lumen is 

 prolonged into the .nephridium for a short distance. Later the cilia 

 are lost, and tke funnels increase greatly in size, while those of 

 neighbouring segments in fact, all the remaining funnels remain 

 stationary for a time, and then become more and more degenerate. 

 The large funnels of the genital segments become the funnels of the 

 vasa deferentia and oviducts ; it will be observed that the number of 

 ovaries and oviducal funnels (two pairs) at first corresponds to that 

 of the testes and sperm duct funnels ; subsequently the gonads and 

 commencing oviducts of segment XII atrophy. Each of these large 

 funnels is continued into a solid rod which passes back through the 

 septum, and then becomes continuous with a coiled tuft of tubules, in 

 which there is an evident lumen, and which is a part of the 

 nephridium of its segment In the segments in front of and behind 

 the genital segments, the rudimentary funnels communicate in the 

 same -way with a solid rod of cells which runs straight for a short 

 dis-ta-nce and then becomes coiled and twisted upon itself and pro- 

 vided with a distinct lumen. In fact, apart from the relative size of 

 the funnels and the presence of the gonads, it would be impossible to 

 state from which segment a given section through the terminal 

 portion of a nephridium had been ta.ken. In a later stage the large 

 funnels of the genital segments become ciliated ; but this ciliation 

 takes place before there is any marked change in the tube which is 

 connected with the funnel. 



