608 
GILBERT E. JOHNSON. 
nepliridium. But this statement is incorrect, foi‘, as has been 
seen, Anton Schneider did not mention the nephridial form. 
It will be seen from the foregoing suiwey that, while almost 
every writer describes the larva ofRh. pellio as living en- 
cysted in the coelom, there are only three who mention the 
nephridial larva. Dujardin called it Dicelis filar ia, 
evidently regai'ding it as a different species from the coelomic 
Bhabditis form. Be Ribaucourt mentions both forms, and 
though unconcerned with their identity, writes as if he 
believed them to be the same species. Lastly K. C. Schneider 
wrongly supposes that Anton Schneider identified the neph- 
ridial form as Rh. pellio, whereas he did not even men- 
tion it.^ 
Thus although the nephridial form is generally supposed 
to be the same species as the coelomic form, Rhabditis 
pellio, it appears that in reality its identity has never been 
determined. 
(2) Nature of the Research. 
The present research, then, was undertaken with the 
object of identifying, and following out, if possible, the life- 
history of the active larval nematode inhabiting the nephridia, 
and in the hope of being able, in so doing, to throw some light 
upon the relations of sex in the group. The work has proved 
exceedingly difficult, and the conclusions reached are in some 
cases largely hypothetical. But the subject is one of great 
interest, and further work should yield valuable results. 
The work has been carried out in the Zoological Laboratoiy 
of the University of Birmingham, under the supervision of 
Professor F. W. Gamble, F.R.S., to whom I am very grateful 
for his unfailing assistance, by suggestion and by criticism, 
throughout the course of the investigation. I am deeplj^ 
indebted to the Board of Agriculture and Fisheries for the 
award of a research scholarship in Agricultural Zoology, with 
the aid of which the latter part of the research has been 
* For a reference to Oi’ley's work, see footnote, p. 622. 
