June is, 1914 
Citrus-Root Nematode 
223 
figures 10 and 11. In the incubation experiments it was thought advis¬ 
able to give the eggs and developing larvae conditions as nearly as 
possible like those in the vicinity of a * .. 
growing Citrus roots. In order that 
uncertainty might not creep into the 
experiments, it was only necessary that 
the material to be placed in the small 
glass brood capsules be Pasteurized at 
a temperature of 130° to 140° F, This 
was done with entire success. Lest 
any misapprehension arise at this 
point, it is well to state that not all 
species of soil-inhabiting nematodes 
are so sensitive to high temperatures. 
It is therefore best to use for incu¬ 
bating material soils as free as pos¬ 
sible from other species of nematodes. 
The form of the brood capsule de¬ 
vised for the incubation experiments 
is illustrated in figure 11. These glass 
capsules are easily constructed and ma¬ 
nipulated, and, as said before, the 
hatching and rearing offer few difficul¬ 
ties. The drawing of the capsule is to 
scale and the explanation is compara¬ 
tively complete, so that nothing need 
be added except to say that the ma¬ 
terial surrounding the egg in the cap¬ 
sule consists of soil particles and Citrus- 
root detritus, both taken from the im¬ 
mediate vicinity of diseased roots of 
Citrus. This material, having been 
Pasteurized, as before described, was 
used as a nidus in hatching Tylenchu- 
lus eggs and rearing the larvae. The 
capsule was half filled with the nidus, 
and then the egg to be incubated was 
introduced by means of a very fine- 
pointed pipette. As this operation was 
accomplished with the aid of a magni- 
fying glass of one-half inch equivalent 
focus, there was proper assurance that 
no other nematode organism was in¬ 
troduced. The remainder of the nidus 
was then inserted above the egg and the disk / introduced. Afterwards the 
disk e was placed in position. Necessarily, considerable water was intro- 
Fig. 7. —Tylenchulus semi penetrans: Young larva 
ol male undergoing the first or second molt. 
Note the deteriorating spear and median bulb, 
indicating that the males are not so well 
equipped to penetrate the Citrus roots as the 
females. The males mature rapldiy, perhaps 
with little or no food, a , I<ip region; a\ lip re¬ 
gion of sloughed skin; b, deteriorating spear; b\ 
spear of the sloughed skin; d t lumen of the 
oesophagus; e, median oesophageal bulb;/, nerve 
ring; g t cardiac oesophageal bulb; h , beginning 
of the intestine; /, large intestinal granule; k, 
small intestinal granule; n, excretory pore; o, 
immature internal sexual organ; l, developing 
male sexual opening; i, terminus. 
