DEVELOPMENT OF ACANTHODRILUS MULTIPORUS. 523 
nephridia. However, my own discovery of numerous external 
pores in each segment of Acanthodrilus multiporus did 
away with some of the difficulties which had been raised by 
Perrier. The whole subject has been recently treated in an 
exhaustive fashion by Dr. Hisig in his magnificent treatise 
upon the anatomy and physiology of the Capitellide; his 
own observations upon the Capitellide led him to confirm the 
view that nephridia and genital ducts in the Oligocheta are 
homologous. As I disagree with Dr. Hisig’s view that the Capi- 
tellide are near akin to the Oligocheta, I should regard his 
very important observations as only furnishing an argument 
from analogy comparable to Mr. Sedgwick’s discovery of the 
complete homology between the genital ducts and nephridia 
in Peripatus. 
The study of the embryology of Lumbricus has thrown 
considerable doubts upon the justice of the view that the 
genital ducts have a relation to the nephridia. Dr. Bergh, 
who is one of the latest investigators of the group, has not 
positively denied any such homology (except in the case of 
the spermathecz), but his observations have shown the com- 
plete independence in development of the sperm-ducts and 
oviducts from the nephridia. The former arise in the first 
place at a considerably later date than the latter, and have no 
relation to them; the septa which bear the funnels of the 
reproductive ducts are also perforated by a nephridium ending 
in the usual fashion in a funnel. Dr. Bergh, however, admits 
that the proved presence of more than a single pair of 
nephridia in a single segment of Annelids does away with the 
force of any arguments which his facts might be supposed to 
lend against the view that the genital ducts are modified 
nephridia. 
Dr. Otto Lehmann (27), who has lately reinvestigated the 
question from the point of view of the development of Lum- 
bricus and Allolobophora, entirely confirms Bergh as to 
the perfect independence of the vasa deferentia and oviducts 
from nephridia ; but he states that the nephridia of the genital 
segments become degenerate ou the appearance of the vasa 
