52-1 ORGANIZATION OF T^NIA SOLIUM. 



only differences that prevail. In the small hooks the anterior process 

 is broader at the end than in the larger ones, and is almost two-lobed 

 the claw is also shorter and narrower, and more bent at the base. 

 The considerable thickness exhibited by the basal portion of the larger 

 claw is due mainly to the fact that it is, so to speak, prolonged further 

 into the posterior process than is the case in the small hooks. To 

 this circumstance is also due in great measure the considerable length 

 of the posterior process, which has already been noticed in the hooks 

 of the anterior row. The solid portion of the process, which is 

 generally marked off from the base by a slight groove, does not 

 measure much more in the anterior hooks than in the posterior ones. 



All these, however, are features which Tcenia solium shares with 

 most of the other large-hooked cystic tape-worms. Much more 

 characteristic is the above-mentioned compressed and rather stout 

 form of the hooks, which, however, can only be rightly appreciated 

 on comparison with those of related species. Another slight difference 

 is that in both small and large hooks, and especially in the latter, the 

 base of the posterior process is somewhat emarginate in the middle. 

 Certain other peculiarities, in regard to the size of the hooks, serve 

 more firmly to establish the diagnosis. The distance of the point of 

 the claw from the end of the posterior process is in the large hooks 

 0-167-0-175 mm., and in the small ones O-H-0'13 mm. (in T. serrata 

 0'25 and 0'14 mm., and in T. crassicollis 0'39 and OvlG), while the end 

 of the anterior process is about as far from the point of the claw as 

 it is from the end of the posterior root-process that is to say, O'09-O'l 

 mm. in the larger hooks, and 0'064-0-07 mm. in the small ones. 1 



The number as well as the size of the hooks varies very much in 

 individual cases. The extremes are somewhat wide apart, for while 

 the smallest number is twenty-two, the largest, according to Davaine, 

 is thirty-two. Most frequently twenty-six or twenty-eight hooks are 

 found, half of them small and half of them large, so that the uneven 

 numbers seem excluded. Bladder-worms which are developed at the 

 same time beside each other appear to exhibit for the most part either 

 one or other of these two numbers. 



The malformations occasionally found in the hooks have already 

 been noticed (see p. 398) ; although, as I see no special mention has 

 been made of this species, yet it was for the most part this species, or 

 rather the corresponding bladder- worm, that I had in view in making 



1 Further measurements are given by Kiichenmeister (" Parasiten," first edition, p. 

 178). I omit these, because I think that the points from which the measurements are taken 

 are much too uncertain to render the size given of much value. In comparing his results 

 with the above statements, I will only mention that his measurements are in all cases 

 somewhat larger than mine. 



