Cobb — Nematodes, mostly Australian and Fijian. 



49 



suction by means of the sucking-bulb, at the same time thrusting forth its spear by 

 means of the muscles attached to its three-bulbed base. The cells of the epidermis of 

 the rootlet having been thus pierced are sucked dry, and at the aperture thus made 



other and deeper cells are similarly attacked. 

 Continuing this line of action, the little worm 

 makes its way into the rootlet, where its 

 presence soon excites abnormal growth, re- 

 sulting in galls, which vary in size, according 

 to the species of plant attacked, from the 

 size of a pin's head to that of a large walnut. 

 In consequence of these attacks, many culti- 

 vated crops, as, for instance, potato, cabbage, 

 banana, pea, bean, members of the melon 

 family, beet, parsnip, radish, tomato, plum, 

 apricot, peach, almond, grape, and many 

 others suffer much or succumb altogether. 

 The worm is a veritable pest in many parts of New South Wales, Queensland and 

 Victoria. 



Soon after the young worm loses its tail the sexual organs begin to develop. 

 The female continues to grow stouter and finally becomes a flask-shaped sac devoid 

 of anus and with a terminal vulva. The two-parted female sexual apparatus develops 

 enormously, and at last almost completely fills the body-cavity, the eggs contained 

 in it numbering several hundred. These undergo segmentation in 

 utero, and are deposited (in the tissues of the attacked plant) con- 

 taining already well-developed embryos. 



Fie. 7. — Neck of the 

 worm shown in Fig. 

 5 more highly mag- 

 nified. 



s, spear ; h, median 

 suoking-bulb ; p, ven- 

 tral excretory pore. 



Fig. 8. — Tylenchus radi- 

 cicola. 



I, a young larva. II, a 

 half-grown female. Ill, 

 a full-grown female. IV, 

 two eggs. V, the vulva ; 

 s, the segments of the egg 

 after the first division. 

 First three figures magni- 

 fied twenty-five times, 

 the others three hundred 

 times. 



as long as 

 gpicuous ; 



The male worm, however, instead of con- 

 tinuing in the path of development followed 

 by the female, returns to a slender adult form,, 

 having the following dimensions and charac- 

 ters : — r2 2^2 ^2-3 3^ Te i'33mm. Cuticula wlth about 

 five hundred transverse striae ; neck conoid, 

 head truncate ; lips six, distinct ; spear stout ; 

 oesophageal tube one-fourth as wide as the 

 neck, lined with thick glistening chitin; median 

 bulb ellipsoidal, two-fifths as wide as the neck, 

 with a large distinct chitinous central part ; intestine two-thirds as 

 wide as the body, its cells closely packed with granules ; rectum twice 

 the anal body-diameter ; tail obliquely hemispherical-conoid ; anus incon- 

 bursa none ; spicula acute, linear, nearly straight, wider and fusiform in 



Fig. 9.— Male of Tylenchus 

 radicicola. 

 I, male worm magnified 60 

 times. 11, head of the same 

 worm magnified 450 times. 

 Ill, male shedding its skin for 

 the last (?) time. IV, cross-sec- 

 tion of the posterior part of the 

 body. V, side view of the same 

 part. VI, side and ventral 

 views of the tail-end. s, spear; 

 6, median suoking-bulb ; sz, 

 spermatozoa ; c, cuticle ; i, in- 

 testine ; V, seminal vesicle ; d, 

 posterior end of the ejaculatory 

 duct ; ps, spicula or penes ; a, 

 anus. 



