642 
GILBEET E. JOHNSOX. 
seems very probable that the mole, thrush and other animals 
Avhich prey on earthworms act merely as carriers o£ the 
nematode. 
(4) Transference of the Nematode from Worm to 
AVorm within the Cocoon. — I endeavoured to discover 
whether the larvas of Rh. pellio are ever transferred 
from the parent worm to the young worm inside the cocoon. 
The cocoons are often plentiful in the soil and can be pro- 
cured by digging. But it is not easy to discover with 
certainty to which species of earthworm they belong, and I 
found it impossible, by digging in the earth, to obtain cocoons 
which I was sure belonged to Lumb. terrestris. An un- 
successful attempt was made to obtain cocoons belonging 
undoubtedly to Lumb. terrestris by keeping a number of 
mature worms of this species under natural conditions in the 
soil, but confined apart from all other species of earthworms. 
I have, howevei', examined many cocoons which I found by 
direct search in garden soil, but without being able to ascer- 
tain to which species they belonged. They were of very 
varying sizes and belonged no doubt to worms of more than 
one species. Nematodes were found living within several of 
them in the albuminous fluid bathing the embryo worm. 
The nematodes were larval and resembled the uephridial form 
of Rh. pellio. I attempted to rear them to maturity in 
order to determine their identity, but was unsuccessful. 
I also removed all the young worms that were ready to hatch 
from the cocoons, killed them and allowed them to decay in a 
little water. Had they been already infected while in the 
cocoon, the nematodes would have appeared when they 
decayed. But this did not happen. 
More evidence is required on this question. Neither the 
identity of the cocoons examined nor of the nematodes found 
inside them was known. But it appears quite probable that 
the larvm of Rh. pellio do not infect the embryonic Lumb. 
terrestris in the cocoon even though they may be present 
with it. 
If the larval nematode found in the cocoon be Rh. pellio 
i 
