218 ENTOZOA. 



the internal water- vascular system, tlie calcareous corpuscles, the 

 marginal transverse foldings of the body, the four suckers, the ros- 

 tellum, and, in particular, the double coronet of hooks. All these 

 metamorphoses have been minutely investigated and described by 

 Leuckart, who also finds that the complete development of the 

 Gysticercus celhiJosce is ordinarily accomplished within the space of 

 ten weeks. 



In its highest grade of formation, the Gysticercus cellulosoB, or pork 

 measle, presents the appearance of an elliptical or reniform hydatid, 

 varying in size from that of a pea to that of a small kidney-bean. 

 The measles present an average diameter of i", but some exceed this 

 considerably. The vesicle displays a more or less opalescent appear- 

 ance, the density being much increased at the side where the head 

 and neck is lodged within the so-called receptaculum, or Goeze's 

 lantern (Figs. 11 — 13, Plate XII). If one such measle be dissected 

 or broken up, it will be immediately perceived that the great vesi- 

 cular portion constitutes the bladder-like caudal extremity of the 

 Gysticercus, whilst the head, neck, and body can be drawn out so 

 as to exhibit a vermiform character. Even before the vesicle 

 is injured, one can readily perceive that these last-named parts lie 

 coiled within the receptaculum in a spiral manner. The neck and 

 body display a series of tolerably regular transverse folds, and on 

 microscopic examination, the cephalic hooks, suckers, and calcare- 

 ous corpuscles are readily brought into view. The hooks, about 

 twenty-four in number, have each a straight shaft, a barb-like 

 anterior root, and a claw-like, sharply-pointed extremity; in 

 other respects they resemble those of the adult tapeworm. In 

 like manner, the calcareous corpuscles, which Smith erroneously 

 designated assimilating cellules, present appearances very little dif- 

 fering from those seen in the fall-grown animal. They consist of 

 clearly- defined, circular, oval, elliptic, oblong, or reniform disks, 

 measuring, according to Smith, from 3^" to fkb" in diameter. 

 Their more intimate structure and nature will be found fully dis- 

 cussed elsewhere in this work. As regards the general structure 



