674 



NATURE OF REPRODUCTION. 



. 215. 



and near its extremity a double crown of curved calcareous processes or 

 hooks, implanted in its substance. There are no distinguishable internal 

 organs, and the caudal vesicle is filled simply with an albuminous 

 watery fluid. Thus there is no apparent source from which these or- 

 ganisms can have come, other than the tissues which they inhabit, nor 

 any visible mode of continuing the species by generation. 



But it has been shown by the investigations of Van Beneden, Leuck- 

 art, Haubner, and Kiichenmeister, 1 that Cysticercus celluloste is only 

 the embryonic progeny of Tsenia soliuin, or the solitary tapeworm, found 

 in the small intestine of the human subject. The specific identity of 

 the two was first suspected from the exact simi- 

 larity in the form and structure of the head and 

 narrow neck, which presents the same sucking 

 disks and double crown of hooks in Tsenia as in 

 Cysticercus. But in Taenia this neck, instead of 

 terminating in a vesicular appendage, is elongated 

 and transversely . wrinkled. The wrinkles, after a 

 certain distance, become deepened into superficial 

 furrows, marking off the body of the animal into 

 oblong divisions or articulations, each articulation 

 showing a double system of communicating vascu- 

 lar canals, and also distinctly marked generative 

 organs of both sexes. As they recede, by succes- 

 sive growth, farther and farther from the head, the 

 generative organs contained in the articulations 

 become more completely formed, and are at last 

 filled with mature fecundated eggs, in which the 

 embryos have begun to be developed. The entire 

 tapeworm then forms a continuous chain or colony 

 of articulations, sometimes from six to eight metres 

 in length, and attached to the mucous membrane of 

 the intestine only by the minute head at its ante- 

 rior extremity. 



By the experiments above mentioned it was 

 found, 1st. That mature articulations from the 

 tsenia solium of the human subject, if administered 

 to young pigs with their food, produce an abundance 

 of Cysticercus cellulosse in the flesh of these ani- 

 mals ; and, 2d. That cysticercus cellulosse from 

 measly pork, if swallowed by man, becomes developed in the intestine 

 within a few days, into ribbon-like worms, distinctly recognizable as 

 young specimens of tsenia solium. 



The manner in which the pig becomes infested with cysticercus is as 

 follows : In the fully-formed tapeworm, in the human intestine, the last 



1 Kiichenmeister, Animal and Vegetable Parasites. Sydenham edition, Lon- 

 don, 1857, pp. 115, 120. 



