ON THE NEMATODES OP THE COMMON EARTHWORM. 633 
(lied before it could reproduce. I represent such an individual 
by the female sign with its circle crossed by a line, to dis- 
tinguish it from those which live long enough to reproduce 
but are for some other reason unproductive. 
The culture was continued on the same lines until it died 
out in the Fg generation. 
Regarding the isolated unproductive females as forming a 
control, the parental generation in this culture appear to have 
reproduced bisexually. The F;^ generation reproduced 
probably as hermaphrodites. The Fg and all subsequent 
generations reproduced unquestionably as hermaphrodites. No 
males were produced in any of the broods. Extraneous males, 
taken from a culture of the nephridial form reared on decaying 
nephridia, were placed with two unproductive females of the 
Fg generation, but did not induce reproduction. 
Culture F. — Ten larvae were taken from the nephridia of 
a freshly killed Lumb. terrestris and isolated in worm 
extract in watch-glasses. Three died while larval. Of the 
remaining seven six developed into females and one into a 
male. The male and one female were killed accidentally. 
Of the other five females three reproduced but two did not, 
although an extraneous male taken from a culture of the 
nephridial form in decaying nephridia was placed with one 
of the latter. 
Ten larvae of the F^ generation were isolated from one of 
the three broods. Eight died while larval. The remaining 
two grew up into females, nor did I see any males among the 
unisolated remainder. One of the two females reproduced, 
the other did not. The culture was continued on the same 
lines until it died out in the F- generation. 
In this culture reproduction was hermaphrodite in all cases. 
Nor were males seen in any of the broods. Further, this is 
the only case in which reproduction has been unquestionably 
hermaphrodite in the parental generation. 
Conclusions. — From the numerous cases of reproduction 
by the females in the absence of males and the finding of 
spermatozoa in the genital organs of such individuals, it is 
