ON THE NEMATODES OE THE COMMON EART'mVOHM. 615 
form is considerably the larger and stouter. Further, its 
reproductive organs ai’e larger than those of the peptone form 
in proportion to the rest of the body, and tbe eggs in the uteri 
of the females are ranch more numerous, although, strangely 
enough, they are individually smaller. Decaying’ earthworm 
is of higher nutritive value than peptone, but it is in several 
respects less useful as a food-medium. Unless specially 
treated beforehand it cannot be employed for nematodes which 
are required to be reared in isolation, for the body-wall 
already teems with nematodes from the nephridia and ccelom. 
In order, therefore, to remove these I pi’oceed as follows. 
A Lumb. terrestris is killed, and from along the whole 
length of the worm is cut a narrow strip of the dorsal part of 
the body-wall, a region to which the nephridia, infested as 
they are with nematodes, do not usually extend. To insure 
the entire removal of the nematodes imbedded in, or encysted 
on, the body-wall or present in any nephridia that may be left 
attached to the strip, the greatest care is exercised. The 
strip is laid on a slide and kept moist with water for about 
two days. During this period it is examined under the 
microscope from time to time. The nematodes which are 
present on the strip of body-wall congregate in the water 
round it, the encysted ones emerging from their cysts as it 
begins to putrefy. Unless the strip is heavily infested they 
can almost all be removed on the point of a fine needle. The 
relative thinness of the body-wall allows a fairly minute 
examination of it as a semi-transparent object, so that nema- 
todes still left buried in the muscular tissue can be dug out 
with a needle, unless too deeply imbedded. When they have 
all been removed the strip is ready for use. A piece is cut 
from it and placed in a watch-glass with a small quantity of 
water and the nematode which it is required to cultivate. A 
control, consisting of another piece of the same strip moistened 
with water, is kept in order to make certain of the entire 
absence of nematodes fi’om the medium employed. Decay is 
rapid, and the nematodes in the cultui’e, like those reared on 
the body-wall decaying in its entirety, attain large dimen- 
VOL. 58, PART 4. — NEW SERIES. 41 
