614 
GILBERT E. JOHNSOX. 
A nearly saturated solution of peptone (Witte’s) was tried 
but this strength proved useless, as the nematodes died soon 
after being placed in it. Weaker strengths were then tried, 
with the same results, until a '15 per cent, solution was reached. 
This, though exceedingly dilute, proved satisfactory for one 
series of cultures. But after that peptone was almost 
uniformly unsuccessful and was abandoned. 
Hay infusion (1 per cent.), like peptone, was successful for 
one series of cultures, but in other cases was unsatisfactory. 
Hay infusion, first sterilised and then inoculated with soil 
bacteria, Avas no impi’ovement. A solution of urea was tried 
but Avas found to be useless. Meat extract and decaying 
meat Avere also unsatisfactory. Since these artificial media 
Avere unsuccessful, the natural food of the nematodes Avas 
used instead. 
Earthworms decaying in damp soil Avere tried, as being 
the natural medium in Avhich Rh. pellio develops. The 
mode of procedure is as folloAvs. A freshly killed Lumb. 
terrestris containing nematodes in the nephridia and coelom 
is opened, and its gut is removed in order to obviate any 
chances of contamination Avith soil nematodes which may 
happen to be passing through in the soil Avhich has been 
swalloAved. The nephridia and the brown bodies in the 
ccelom are left remaining. The Avorm is placed Avith soil in 
a watch-glass and then moistened Avith water. The soil is 
first heated to kill off any soil nematodes in it. But the 
temperature required to make certain of having done so 
probably renders it sterile and therefore valueless. At any 
rate, I find that it can be dispensed Avith. Within a Aveekthe 
decaying worm is seen to be covered Avith a whitish mass of 
actively Avrithing nematodes. Examination shows these to be 
adult males and females, the latter being the larger. Several 
generations are produced before the nutriment provided by 
the rotting carcase of the Avorm is exhausted. On comparing 
these adults obtained from the putrefying Avorm with those 
reared in peptone or hay infusion the difference in size is seen 
to be very striking (PI. 37, figs. 2 and 3). The putrefaction 
