370 



THE DEVELOPMENT OF CESTODES. 



FIG. 215. Cysticercoid Tetrarhyn- 

 chus from a Mediterranean Percoid. 

 A, in its natural position ; Jt, with 

 evaginated body. ( x about 20.) 



On the other hand, it is true that the Cysticercoid nature of the 

 Anthocephali has been doubted. My uncle F. S. Leuckart explained 



the latter, in opposition to Rudolphi, as 

 young Tetrarhynchi (or Bothriocephali), 

 and denied the interpretation of the 

 surrounding bladder as a caudal bladder, 

 since even in examples sent by Kudolphi 

 (A. gracilis) both Bremser and he 

 found the posterior end of the tape- 

 worm free and without any connection 

 with the surrounding bladder, and 

 could not perceive any rupture in it. 1 

 We now know that both investigators 

 were right. 2 



In spite of their considerable size, the AnthocepJiali belong, how- 

 ever, to the parenchymatous bladder-worms. Instead of water, they 

 contain (see Fig. 219) an areolar connective tissue, which fills 

 the whole of the interior, and is in continuous connection with the 

 external envelope of the body. 3 This circumstance also explains 

 how the Anthocephali, and especially the larger ones, instead of 

 developing into balls, stretch out longitudinally, and sometimes 

 assume an almost tape-worm-like form. This is most striking in the 

 species (Anthocephalus s. Gymnorkynchiw reptans) living in the 

 muscles of Brama Raji, which in course of time becomes a ribbon 

 almost a yard long, and only exhibits a ball-like swelling near the 

 anterior end where the receptaculum with the head is placed. 



The appearance of ttye head after development is always the same 

 as in the adult tape-worm. It forms a solid mass with outwardly 

 directed suctorial pits, and, as in the majority of the Cysticercoids, 

 is raised like a plug from the floor of the receptacle with which 

 it is at first always in continuous connection (Fig. 215). In many 

 species this connection is permanent, so that the receptacle distinctly 

 appears as an integral portion of the tape-worm, like the evaginated 

 neck, which, in the other Cysticercoids, is generally the means of con- 

 nection with the caudal bladder. In other species, however, the 

 former connection is dissolved when the head is perfectly developed, 

 and then the latter lies quite free in the interior of the former neck, 

 as my uncle quite correctly observed within the first twenty years of 



1 Zoologische JBruchstiicke, Heft i., p. 67, 1819. 



a See in regard to this v. Siebold's " Abhandlung iiber den Generationswechsel der 

 Cestoden," Zeitschr. f. wis*. Zool., Bd. ii., p. 200, 1850, and van Beneden, Mtm., &c., 

 p. 76. 



8 Hoek, "Ueber den encystirten Scolex von Tetrarhynchus, " Niedcrldnd. Archiv f. 

 Naturwiss. 1879. 



