296 ENTOZOA. 



remark, as Weinland lias likewise done, that Creplin once discovered 

 a Botlirioceplialus in a cat — a circumstance whicli led him to con- 

 clude that it had been accidentally introduced by the animal's 

 " eating fish containing the larva of that worm." 



As regards the structural peculiarities of the adult Bothrio- 

 cephalus, I need only dwell upon those which are more obviously 

 characteristic, inasmuch as I have already enumerated those of a 

 general nature. In the living condition, the body of the animal is 

 highly contractile, especially in the region of the so-called head ; 

 the latter organ altering its form very materially at different times. 

 Unlike ordinary cestodes, the Bothriocephalus latus very seldom 

 breaks up into separate fragments, and never, apparently, into 

 independent living proglottides. The integument presents nothing 

 peculiar ; and, according to Leuckart, the muscular layers are feebly 

 developed, only a few calcareous corpuscles being scattered about 

 the parenchymatous substance, here and there. The tissues of the 

 body generally are remarkably transparent, the external paren- 

 chyma displaying "numerous rounded granular masses, which 

 appear as opaque points," and impart to the tissues a yellowish 

 grey colour. In each segment a well-defined internal membrane 

 separates the central visceral mass from the surrounding external 

 parenchyma of the body. The water- vascular system (as Esch- 

 richt long ago pointed out) is characterized by two main longitu- 

 dinal channels, from which no transverse canals have yet been seen 

 to pass ofi*; but Knoch af&rms that throughout the segments there 

 is a superficial vascular network, which communicates with the 

 great longitudinal vessels ; and he has, moreover, observed 

 granular movements in their interior, which he believes to be due 

 to the presence of cilia. The main canals lie midway between the 

 lateral borders and the central axis of the body, and, according to 

 Von Siebold, terminate in the head by dividing into several fine 

 branches. 



Speaking generally, the disposition of the reproductive organs 

 internally corresponds in a great measure with that of the Taania? 



