Coss—Nematodes, mostly Austrahan and Fijian. 297 
weaker tube, which passes through the oblique nerve-ring, situated just behind the 
median bulb. The posterior bulb may become rudimentary, but probably never quite 
disappears. The 
female sexual apparatus is usually single and asymmetrical, beng in that case usually 
straight and directed forward though often presenting a rudimentary posterior branch, 
In the former case the vulva is behind the 
Lateral organs as well as visual organs are unknown in the genus. 
but it may be double and symmetrical. 
middle; in the latter case it is central. 
spicula and in most species a more or less well developed bursa. 
The male possesses two equal slightly arcuate 
87:9 
see aS is the formula for the freshly hatched 
iy ieradicicola, Greef.) “s1--assea-30 
larva, of which the following is a further description :—Cuticle traversed 
by about five hundred transverse strie; neck cylindroid to opposite the 
base of the buccal cavity, but thence to the mouth is convex-conoid ; 
faint indications of lips; three-bulbed spear 

Fic. 4.—Larva of Tylenchus 
when at rest drawn back so that its apex is aa 

I, the larva magnified 190 
times. II, head of the same 
worm magnified 875 times. 
III, small section of the body 
magnified 750 times. IV shows 
at the centre of the circle 
the actual size of the worm. s, 
spear; 6, median sucking-bulb ; 
n, nherve-ring ; p, ventral excre- 
tory pore ; posterior }, cardiac 
bulb ; 7, the intestine ; ¢c, the 
cuticle ; /, the lateral wings of 
the cuticle. 
removed half the spear-length from the mouth; 



ellipsoidal sucking-bulb just in front of the 
TL 
nerve-ring ; posterior cesophageal swelling weak | ae 
and devoid of chitin; intestine pellucid, two- 3 
; 
thirds as wide as the body, and having its cells 
roe 

closely packed with granules ; ventral excretory 
pore just opposite the commencement of the 
intestine ; lateral wings occupying an area one-fourth as wide as the 
body and presenting four parallel lies ; tail conical from the incon- 
spicuous anus ; caudal glands absent, terminus pointed. 
The larve, which are found in large numbers in the cavities occupied by the 
parasitic mother-worms, and also in the sur- 
rounding soil, make their way into the rootlets 
of various plants by means of the special 
piercing and sucking apparatus, namely, the 
spear and bulb, and then undergo a remark- 
able metamorphosis. At an early moult they 
lose the conical tail and the posterior end 

Fic. 6.—Immature Ty- 
lenchus  radicicolu 
Fic. 5.—Young of Ty- 
becomes rounded. Meanwhile the body, amply 
nourished by plant-juices, becomes plump, and 
takes on the dimensions shown in the fol- 
lowing formula and the adjacent illustrations : 
AD UisObeoY: OL: 
337-95 tei ¢ Lhe larva makes its way into a 
lenchus radicicola, 
after entering a 
root. 
s, spear; b, sucking- 
bulb ; p, ventral excre- 
tory pore ; 7, intestine ; 
v, unicellular ventral 
gland ; a, anus, 
shedding its skin. 
c, the old skin being 
cast off; s, the old and 
the new spear; p, the 
ventral excretory pore ; 
v, the unicellular ven- 
tral gland ; 0, rudimen- 
tary sexual organs. 
rootlet by applying its mouth to the surface of the rootlet and exerting a powerful 
00 
