520 ¥. W. GAMBLE AND J. H. ASHWOBTH. 



while in Benham's specimen the nephridia are about '.S mm. 

 long. 



A. ecaudata. — A post-larva, 7-2 mm. long, was embedded 

 in paraffin, and cut transversely as far back as the beginning 

 of the nephridial region. The remainder of the specimen 

 was afterwards cut sagittally until the middle line, as indicated 

 by the nerve-cord, was reached ; the paraffin was then 

 thoroughly removed from the portion of the worm still in the 

 paraffin block by solution in xylol, and the half of the ali- 

 mentary canal remaining in the body of the worm dissected 

 out, thus leaving only the body-wall and the nephridia 

 attached to it. The object was then transferred to thick 

 cedar-wood oil, in which it became transparent, thus enabling 

 the observer to examine the nephridia in detail. The object 

 as it now appears is represented in PL 26, fig. 50. 



The nephridia of this specimen are all provided with 

 funnels ; the anterior ones are large, but the posterior ones 

 are much smaller. The thick lips of the funnel are formed 

 by cubical ciliated cells, the greater part of which is occupied 

 by the deeply staining nucleus. The long cilia of these cells 

 hang into the mouth of the funnel. On the dorsal lip of the 

 second nephridium there is at one point a small conical heap 

 of cells, the commencement of the first vascular process of 

 the lip. The funnels of several of the nephridia are bent 

 or twisted upon themselves ; those of the last four or five 

 nephridia are smaller and simpler than the anterior ones. 

 The funnels of the ninth and tenth nephridia are connected 

 to the secreting portion of the organ by an elongated narrow 

 tube ('06 mm. and '1 mm. in length respectively) ; those of 

 th.e other nephridia are almost sessile upon the secreting por- 

 tion of the organ. The secretory portion of the nephridium 

 is a somewhat irregular, thin-walled, hollow sac, the walls of 

 which are formed by a single layer of ciliated columnar cells 

 whicli contain very numerous excretory granules, which stain 

 black with iron-heematoxylin. There is no line of demarca- 

 tion between the secretory and terminal portion of the 

 nephridium. The cells of the latter also contain excretory 



