ON THE NEMATODES OF THE COMMON EAETHWORM. 641 
the rectal contents of one of the moles. All the larvse were 
similar in size and appearance to the larv^ of Rh. pellio 
except these last, Avhicli were stouter and rather blnnter- 
tailed. I tried to rear these and the encysted larvse to 
maturity for the purpose of ascertaining whether they were 
Rh. pellio, but I was unsuccessful. No adult nematodes were 
seen. It appeal’s likely, then, that the larvse of Rh. pellio 
which are in the earthworm when the latter is swallowed by 
the mole succumb to the action of the digestive juices in 
their passage down the alimentary canal, or, if they survive, 
do not remain and mature but escape with the excrement 
into the soil. 
The droppings of several thrushes were examined while 
still moist, and were found to contain a large number of larval 
nematodes similar in appearance and size to the nephridial 
larvse of Rh. pellio. All were dead. But death may have 
been due, not to the effects of the passage through the gut, 
but to the frosts which prevailed at the time when the fseces 
were deposited. Other freshly dropped fseces of a bird have 
been found to contain living larval nematodes, showing that 
nematodes can survive a passage through the gut. 
Manpas (10, p. 624) says that the larvse of Rh. pellio are 
plentiful in all the slugs around Algiers. Whether the slug 
is an alternate host to the earthworm is not clear. But the 
impression conveyed is that the nematode can live equally 
well in the body of either and may pass quite casually into 
one or the other. 
In this connection it might be mentioned that several 
attempts were made to rear again to maturity on decaying 
body-wall find on “extract” of Lumb. terrestris the larvm 
which were obtained in the experiment with the worm decaying 
in soil in the glass dish. But fill failed. This might be taken 
as an indication that an alternate host is necessary, but 
it is more likely that failure was due to other causes. 
It was not discovered, therefore, whether the life-cycle of 
Rh. pellio is divided into two periods, one spent in the 
earthworm and the other in an alternate host. But it 
