522 ORGANIZATION OF TVENIA SOLIUM. 



On a former occasion, I have described the very various positions 

 which are characteristic of the suckers of Tcenia solium (p. 513). 

 They may be moved singly or in pairs, opposite to each other, or the 

 whole four may be raised up like arms, extend in different directions, 

 and then contract. Displacements of the rostellum are generally as- 

 sociated with these movements, and indeed so constantly, that there 

 is an unmistakeable connection between these various actions. This 

 is very marked when the suckers feel about in front as though trying 

 to fix themselves to some object situated in front of the head. As 

 often as this motion takes place, the apex is observed to sink in, and 

 to remain for a time in this position, before again protruding and al- 

 lowing the hook-apparatus to unfold itself. 



When we remember that this is the way in which the suckers 

 attach themselves to the wall of the intestine, and press the front 

 of the head against it, it will be seen that on the protrusion of the 

 apex the points of the hooks must press into the wall of the intestine 

 and penetrate the deeper the further they are removed from the apex ; 

 and as the apex at the same time, by the flattening of the formerly 

 cup-like rostellum, drives the points of insertion of the hooks further 

 from each other in a radial direction, the fastening is of course made all 

 the stronger, sufficient in fact to keep the body in its position without 

 the help of the suckers, and to present the necessary resistance to the 

 pressure of the chyle. 



A separation may take place when the worm is not fixed too 

 deeply by a rupture of the intestinal villi, in consequence of the 

 tension exerted on the body of the worm, and thence transferred to 

 the extended hooks. It may happen, too, that the hooks straighten 

 themselves up and relax their hold of the surrounding tissue. 



The manner in which the rostellum is concerned in all these pro- 

 cesses need not be again discussed, after our former remarks regarding 

 the motor mechanism of the hooks (p. 401). It is equally unneces- 

 sary to explain the structure of the rostellum and the associated 

 muscular disc, or to discuss the nature and mechanism of the suckers 

 (see p. 395). In regard to all these parts, we need only remark that 

 they do not differ in any respect from the usual conditions of the 

 cystic tape-worms. It is true that Nitsche attempted to establish 

 certain peculiarities in regard to the structure of the muscles of the 

 circlet of hooks in Tcenia solium, but this was probably due to the 

 unsatisfactory nature of his material. In reality the structure of T. 

 serrata is exactly repeated in Tcenia solium. Especially is it impos- 

 sible to regard the pouches intended for the reception of the roots 

 as a special characteristic of Tcenia solium, although they were 

 the occasion of Kiichenmeister's proposal to renounce the apparently 



