688 THE ANATOMY OF BOTHRIOCEPHALUS LATUS. 



phalus latus," Zeitschr. f. wiss, Zool., Bd. xxii., pp. 40-99, 1872 ; also as first part of 

 " Beitrage zur Anatomie der Plattwurmer," Leipzig, 1872. 



Moniez, "M^moire sur les Cestodes," pp. 125-183, Paris, 1881; also in Traveaux 

 de I'Inst. de Lille, t. iii., fasc. 2. 



When, in the year 1860, 1 was working at the structure of this 

 worm in preparing the first edition of this book, only the first of the 

 above-named memoirs had been published, and although it still forms 

 the basis of our knowledge of the anatomy of Bothriocephalus, it is 

 markedly defective, in the absence of any discussion of the relations of 

 this species to the other Cestodes. This defect tended to produce the 

 impression that the peculiarities of Bothriocephalus were much more 

 fundamental than is really the case. What Eschricht omitted, I 

 have attempted to supply. Since then we have learnt that this worm 

 is, in its general structure, at least in the general disposition of its 

 organs and in the nature of its tissues, closely allied to the Tcenice, 

 although strikingly different from them in other respects, especially 

 in the structure of its generative organs. In my description of the 

 latter I unfortunately fell into a misconception in regard to the yolk- 

 gland, which had been rightly interpreted by Eschricht and subse- 

 quently by V. Siebold, but which I mistakenly regarded as a deposit 

 of excreted matter. To Stieda is due the credit of discovering this 

 error, as also of elucidating our conception of the structure of the 

 genital apparatus by his discovery of the vaginal sheath, which had 

 been overlooked. What subsequent investigators have done has been 

 essentially little more than an extension and correction in matters of 

 detail. We shall find occasion to allude to these contributions in the 

 description which follows. 



As we have already noted, Bothriocephalus agrees in its general 

 structure with the Tcenice. In both can be seen (best in thin trans- 

 verse sections) the same cuticle, with the subjacent, crossed fibrous 

 layers, the same cortical and central layers, and the same disposition of 

 the generative organs. The latter lie, as in Tcenice, for the most part 

 within the central layer, the male generative glands and the vas 

 deferens turned to the dorsal surface, the uterus and ovary towards 

 the ventral, where the generative openings are also situated. The 

 only thing which seems unusual in Bothriocephalus is the presence 

 of numerous large heaps of granules, lying in a layer between the 

 subcuticular layer and the longitudinal cortical muscles, which they 

 push out to a considerable extent, especially in the lateral regions of 

 the segments. These are the structures which I formerly erroneously 

 regarded as deposits of excreted substance, although they had been 

 already shown by Eschricht to be connected with the female organs, 

 and had been described as ormnswhich ihough not ovaries, played a 



