452 



MALFORMATIONS OF TJUNIA SAGINATA. 



same chain, as is the case also with the more marked divergences. 

 Especially interesting in this connection is the specimen observed and 

 drawn by Weinland, whose joints showed, as he says, an unusual 

 " tendency to bifurcation." 



I need say little further regarding the structure of the generative 

 organs in these double joints. Each division has of course special 

 genitalia, as a rule quite perfectly developed, though their extremities 

 may perhaps be abnormally approximated. This is even better 

 marked in the case of the undivided side than of the divided, in 

 which, as a rule, the outer border possesses a greater length, and that 

 becomes the more marked the further the dividing line intrudes. In 

 the face of such facts, we cannot close our eyes to the presumption 

 that there is a certain connection between the growth in length 

 and the boundaries of the individual proglottides. 



The greater length of the divided side also causes the furrow 

 separating the two parts of such a double joint to incline forwards in 



a diagonal or curved line. Usually it 

 disappears sooner or later about the 

 middle, but it sometimes happens that it 

 extends to the anterior border. The 

 anterior half then acquires the form of 

 a superfluous joint, and this becomes 

 wedged-in on one side of the chain, be- 

 tween the divergent proglottides, as shown 

 by the first of the annexed figures (Fig. 

 259, A), which is taken from one of Dr. 

 Schmidt's preparations. The inner side 

 of the supernumerary joint was degene- 

 rated, as the wedge-like shape suggests. 

 The second figure (B) shows a very similar 

 appearance, which was reported to me a 

 long time ago by my late friend and 

 countryman Dr. Kriiger of Brunswick. 



I must, however, leave it undetermined whether the explanation 

 here proposed be the right one or no. Moniez would prefer to deduce 

 the supernumerary wedge-shaped joint from reduplication at the 

 point of proliferation, and would therefore suppose that, instead of 

 one joint, two had formerly arisen beside one another. In the forma- 

 tion of such supernumerary joints he sees the beginning of the double 

 chains of Tcenia marginata (p. 398), which are distinguished by the 

 fact that the doubling of the point of proliferation persisted for a 

 longer time, and gave rise to a whole supernumerary chain instead bf 

 only to a single joint. 



FIG. 259. Supernumerary joints 

 of Tcenia sayinata (nat. size). 



