CONTRIBUTIONS TO THE ANATOMY OF EARTHWORMS. 439 
Pericheta is like that of the immature Acanthodrilus 
georgianus; the resemblance is not due to a corresponding 
immaturity of condition, for the diverticula were in every case 
crammed with spermatozoa, which, however, only occupied the 
cavity of the diverticulum, and had no relation whatever with 
its epithelium. 
It seems to be clear from the foregoing description that the 
diverticula not only perform a different function 
from the spermathece, but that the diverticula of 
some species (e.g. Pericheta) differ from those of 
other species (e.g. Acanthodrilus). Now, the presence 
of diverticula is so very general among Earthworms that they 
are probably to be looked upon as very ancient organs!; their 
great diversity of form and structure is also an argument 
leading to the same conclusion. It has been suggested by 
myself (9) and by Hisig (17) that the diverticulum is the 
remnant of the glandular part of the nephridium, out of part 
of which the spermatheca has been developed. This sugges- 
tion does not commend itself to me now, for the reason that in 
no species of Pericheta, or any other worm in which the 
vephridial system is in an archaic condition, is there any clue 
to the origin of the diverticula. If it be ultimately proved 
that the nephridial system of Pericheta, Megascolides, 
&c., is not archaic but greatly modified, then the above sug- 
gestion will have to be reconsidered. 
The nature of the spermathecal diverticula can hardly be 
considered apart from the spermathece themselves with which 
they are so intimately connected. I am not certain, however, 
that from the developmental point of view the term “ diver- 
ticulum” is not a misnomer. In the immature spermathece 
of Acanthodrilus georgianus, to which reference has 
already been made, the connection of the diverticulum with 
the spermatheca is by an extremely fine cord of cells in which 
no lumen could be detected; the relative perfection of the 
distal part of the diverticulum as compared with the proximal 
1 There are very few genera in which they are absent; Lumbricus 
Allolobophora, Hormogaster, are principal ones. 
