640 
GILBERT E. JOHNSON. 
further. I do not know whether at the commencement only 
one or more than one generation of offspring was produced, 
hut the larvm were no larger at the end of the experiment 
than when I first examined them shortly after the com- 
meuceineut. 
'fihe results of this experiment would seem to indicate 
that the offspring of the nematodes which mature and rejjro- 
duce in a worm that dies and decays in the soil are able to 
wander away from their food-supply after (or even perhaps 
before) it is exhausted and pass a period of free existence in 
the earth, perhaps only until the earliest opportunity arrives 
of infecting a fresh worm. It appears that, before leaving 
the carcase of the worm, they have reached the stage of growth 
coi responding to that of the larvae found in the nephridia, and 
while free in the soil do not under ordinary circumstances, 
outgrow this stage. I have shown, however, in the previous 
secDion the difficulty of finding the larvae of Rh. pellio 
in the soil to prove this. 
(3) No Alternate Host discovered. — Since earth- 
worms fall a prey to moles, thrushes, blackbirds, rooks and 
many less highly organised animals, it was only to be expected 
that Rh . pellio would be met with in connection of one sort 
or ainother with them. The larval nematodes which ai-e eaten 
with the worm might succumb to the action of the digestive 
juices or travel unharmed through the alimentary canal and 
out into the earth with the faeces or pass ai period of their 
existence within the body, either remaining larval or attaining 
sexual maturity. 
The alimentary canals of four moles were examined on 
ditlerent occasions. They had been feeding on earthworms 
amongst other thiugs, as was evident from the presence of 
setae aiud portions of nephridia among the contents of the 
stomach. Larval nematodes, both free and encysted, were 
found in the stomach and intestine. The cyst of one of the 
encysted individuals was open at the end, and the nematode 
inside it was seen to be alive. All the unencysted individuals 
were dead, except a few which appeared after two days among 
