ACANTHOCEPHALA 341 



LITERATURE. 



ALDROVANDI, U. De animalibus insectis, 1638, Book VII., Chap, x., p. 720. 

 DEGLAND, C. D. Descr. d'un ver filiforme rendu par vomiss. (Rec. trav. soc. d'amat 



d. sc., de 1 1'agricult. et des arts de Lille, 1819-22, p. 166.) 

 SIEBOLD, C. TH. v. Ueber d. Fadenwiirm. d. Insect. (Stett. entom. Ztg., 1854, 



xv., p. 107.) 

 DIESING, C. M. Rev. d. Nemat. (Stzgsb. k. k. Ac. d. Wiss. Wien. math.-nat. Cl.. 



1880, xlii., p. 604.) 



PATRUBAN, v. Vork v. Gord. aq. b. Mensch. (Wien. Med. Jhrb., 1875, p. 69.) 

 CAMERANO, L. Ric. int. al parassit. ed al polimorf. dei Gord. (Mem R. Ace. sc., 



Torino, 1887 [2], xxxviii., p. 395.) 

 Monografia d. Gordii. (Ibid., 1897, xlvii.) 

 BLANCHARD, R. Pseudoparas. d'un Gord. chez l'homme. (Bull. Ac. de med. de 



Paris, 1897, xxxvii., p. 614.) 

 TOPSENT, E. Sur un cas de pseudopar. chez I'homme du Gord. viol. (Bull. soc. 



scient. et med. de 1'Ouest., 1900, ix., No. i.) 

 PARONA, C. Altro caso di pseudopar. d. Gordio nell' uomo. (Clinica Med. Ann., 



1901, No. 10.) 



D. ACANTHOCEPHALA (Rud.) 



Gutless, nematode-like worms that carry at their anterior end a retractile 

 rostrum beset with hooks. In their adult condition they only live in verte- 

 brate animals. During their larval stage they are often parasitic in inverte- 

 brate animals. 



The Acanthocephala are elongated cylindrical worms, with a rounded 

 posterior end. In some species an annulation is distinctly recognisable ; 

 they are, however, not segmented. The size varies according to the species, 

 between about 5 10 mm. and 40 50 cm. ; in general, however, there is a 

 preponderance of the small species. The sexes are separate, and the males 

 can easily be distinguished from the females without examination of the 

 genitalia, as the females are both larger and thicker. 



The body wall of Echinorhynchus is limited by a thin cuticle, 

 which is attached inwardly to the hypodermis. In only exceptional cases 

 a syncytium with large nuclei, even in the adult condition, is represented 

 by the hypodermis ; and in it fibre systems, the elements of which run 

 in layers in various directions, appear, and it is only towards the interior 

 from these strata of fibres that the nuclei of the hypodermis are found. 

 As a rule, these fibres, at all events the radiary fibres, are regarded as 

 muscles. Hamann describes them as elastic fibres, which lie in a viscid 

 gelatinous connective substance (transformed protoplasm ?) ; a lacune system 

 filled with a granular fluid, the central part of which are two longitudinal 

 lacunes lying at the sides, also belongs to the cutaneous strata, as do the 

 so-called lemnisci, two short, flat organs suspended in the body cavity, and 

 the pedicles of which are attached anteriorly at the border between the 

 rostrum and body; their structure as well as their origin permit them 

 to be traced to the skin (fig. 223). 



Finally, inwardly below the skin there follows a layer of annular, and after 

 these a layer of longitudinal muscles, the structure cells of which remain 

 present in the residues, carrying nuclei. The motor apparatus of the rostrum, 

 the sheath of the rostrum, and the lemnisci also belong to the muscular 



