DEVELOPMENT OF ACANTHODRILUS MULTIPORUS. 519 
solid and lose their cilia; this condition is seen in the newly 
hatched worm, where, however, there is hardly a trace of the 
funnels. It is, therefore, perhaps surprising to find that four 
out of these funnels commence to grow again and a second 
time acquire cilia, serving as the funnels of the genital ducts in 
the adult worm. This led me to suspect that the funnels 
might possibly be new structures, and that the original nephri- 
dial funnel might be present and connected with the nephridial 
tubule which I have described as the commencing sperm-duct or 
oviduct. I should remark, however, first of all that the loss of 
cilia in a cell (Protozoa) is not necessarily a prelude to de- 
generation ; on the contrary, it is sometimes followed by a 
specially marked activity of division. Besides, the solidifica- 
tion of that portion of the nephridial duct which is connected 
with it might be looked upon in the same light, as it is un- 
doubtedly at first furnished with a wide lumen which is 
ciliated. But the outgrowth of a tube from this, which I 
have figured (fig. 11) as nearly reaching the exterior, is 
hardly an indication that the structure in question is really 
degenerating. There seems to be no doubt, however, that, 
with the exception of those in Segments 10—13, the original 
nephridial funnels do ultimately disappear, or are represented 
by the merest traces. 
On the hypothesis that the structures which I have identified 
with the nephridial funnels of Segments 10, 11, 12, and 13, 
are really new structures, and not the persistent funnels, some 
traces of the latter should be forthcoming. I could not, how- 
ever, detect any such traces. Yielding this point for the 
moment, it would be sufficient as an argument for the time 
being if there were no clear connection between the large 
funnels of the genital segments and the nephridial tubule ; 
this connection, however, is quite unmistakable. 
It seems, therefore, difficult to explain the connection of the 
funnels of the genital ducts with nephridia except on the hypo- 
thesis, supported by other facts, that the funnels in question 
are the persistent and enlarged nephridial funnels. I do 
admit, however, that this is by no means necessarily a proof 
