NEMATHELMINTHES 



241 



appended to tlie worm as a liernia-like body. The intestine 

 of the latter degenerates, so that here also nutrition must 

 take place by endosmosis. The course of development of 

 Atractonema resembles that of Sphssrularia. The eggs 

 arrive in the body cavity of the host, and the young worms 

 from here repair to the outside world, where they develop 

 into sexually mature animals and copulate. The fertilized 

 females penetrate into the larvoe of a gall-fly, Cecidomya 

 jpini, where they undergo their further development. 



To the developmental processes of the forms last con- 

 sidered can be added that of the Beet Nematode, Heterodera 

 Schachtii. Swellings containing a spherical worm filled with 

 eggs, which can be recognized as a Nematode by its develop- 

 ment, are often found on the lateral roots of the sugar-beet. 

 The eggs of the worm develop within it, and pass into a 

 slimy brood-sac, secreted by its genital ducts and attached 

 to its posterior end. From hei'e the larva passes to the out- 

 side world, and undergoes a development which dilfers 

 somewhat according as a male or a female arises from it. 

 The female, which is provided with a stiletto-like structure 

 on the pharynx, bores into a beet-root,'moults here, and sucks 

 up such a large amount of nourishment that it becomes 

 swollen into a plump body, and thereby causes the epidermis 

 of the root to burst. In this way the hind end of the 

 female is exposed, and it is probable that copulation does not 

 take place until this time (Strubell). 



Probably the most profound metamorphosis undergone by 

 any Nematode is exhibited by AUantonenia tnirab'de, likewise 

 discovered by Leuckart (No. 7), a worm of a sausage-like, 

 stubby shape, which lives in the body cavity of one of the 

 CurculionidEe {Eylobius pini). Except for the form of the 

 sexual apparatus and its products, resemblance to a Nematode 

 could be recognized neither from the external nor internal 

 conditions of this intestineless structure. This worm is said 

 to be hermaphroditic, and it is maintained that self-ferti^ 

 lization takes place. The eggs are developed in the uterus 

 into young Nematodes, which are set free in the body cavity, 

 and subsequently reach the outside world through the intes- 

 tine. For a considerable time the larvae lead a free life, for 



K. H. E. R 



