NEMA TEL MINTHES. 3 1 3 



canal of their host, through the walls of which they make their way, and 

 travelling along lines of connective tissue pass into the muscles. Here the 

 embryos, which are born in a very imperfect condition, rapidly develop, 

 and eventually assume a quiescent condition in a space inclosed by sarco- 

 lemma. Within the sarcolemma a firm capsule is developed for each larva, 

 which after some months becomes calcified; and after the atrophy of the 

 sarcolemma a connective tissue layer is formed around it. Within its 

 capsule the larva can live for many years, even ten or more, without 

 undergoing further development, but if at last the infected flesh is eaten by 

 a suitable form, e.g. the infected flesh of the pig by man, the quiescent 

 state of the larva is brought to a close, and sexual maturity is attained in 

 the alimentary tract of the new host. 



Gordioidea. The free larva of Gordius already described usually pene- 

 trates into the larva of Chironomus where it becomes encysted. On the 

 Chironomus being eaten by some fish (Villot, No. 39) (Phoxinus Itevis or 

 Cobitis barbatula), it penetrates into the wall of the intestine of its second 

 host, becomes again encysted and remains quiescent for some time. Event- 

 ually in the spring it leaves its capsule, and enters the intestine, and 

 passes to the exterior with the feces. It then undergoes a gradual meta- 

 morphosis, in the course of which it loses its ringed structure and cephalic 

 armature, grows in length, acquires its ventral cord, and on the develop- 

 ment of the generative organs loses the greater part of its alimentary tract. 



Young examples of Gordius have often been found in various terrestrial 

 carnivorous Insecta, but the meaning of this fact is not yet clear. 



BIBLIOGRAPHY. 



(383) 0. Biitschli. "Entwicklungsgeschiclite d. Cucullanus elegans." Zeit.f. 

 wiss. Zool., B. xxvi. 1876. 



(384) T. S. Cobbolcl. Entezoa. Groombridge and Son, 1864. 



(385) T. S. Cobbolcl. Parasites ; A Treatise on the. Entozoa of Man and Animals. 

 Churchill, 1879. 



(386) 0. Galeb. "Organisation et developpement des Oxyttrid^s," &c. Archives 

 de Zool. exper. et gener., Vol. vn. 1878. 



(387) K. Leuckart. Untersuchungen iib. Trichina spiralis. 2nd ed. Leipzig, 

 1866. 



(388) E. Leuckart. Die menschlichen Parasiten, Bd. u. 1876.' 



(389) H. A. Pagenstecher. Die Trichinen nach Versuchen dargestellt. Leipzig, 

 1865. 



(390) A. Schneider. Monographie d. Nematoden. Berlin, 1866. 



(391) A. Villot. "Monographie des Dragoneaux" (Gordioidea). Archives de Zool. 

 exper. et gener., Vol. in. 1874. 



ACANTHOCEPHALA. 



The Acanthocephala appear to be always viviparous. At the. time of 

 impregnation the ovum is a naked cell, and undergoes in this condition the 

 earlier phases of segmentation. 



The segmentation is unequal (Leuckart, No. 393), but whether there is an 

 epibolic gastrula has not clearly been made out. 



Before segmentation is completed there are formed round the ovum 

 thick protecting membranes, which are usually three in number, the middle 

 one being the strongest. After segmentation the central cells of the ovum 

 fuse together to give rise to a granular mass, while the peripheral cells at a 

 slightly later period form a more transparent syncytium. At the anterior 



