182 s. GOTO. 



tlie .surrounding- niesendn-niM by a layer of dense connective tissue 

 (Fig. 2, t& Fig. 18). During the winter season, it is a solid mass of 

 vesicular cells that have assiuned a polyhedral form by their mutual 

 pressure. Each cell encloses a conspicuous round nucleus, which 

 seems to be provided with a wall of its own, and in which numerous 

 chromatin particles are to be observed. The cytoplasma is a hyaline 

 fluid which scarcely takes up any color. The nuclei are of various 

 sizes in the same lobe, some being very small, leaving abundant 

 space for the cytoplasma, while others are of such a size as nearly to 

 h II up the entire cavity of the cell. 



From the anterior end of the testis proceeds a single vas 

 deferens, which passes anteriorly in a straight coiu'se dorsal to the 

 oviduct and ventral to the yolk-duct. Daring the first part of its 

 course, it lies ventrally to the uterus ; but at al)out the level (^f the 

 anterior end of the ovary, it turns dorsal to it and opens info the vitel- 

 line duct of the other indiridaal a little more anteriorly than the an- 

 terior end of the ovary. Zeller" represents the vas deferens of one 

 individual as standing iu direct connection with the " Laurer's canal" 

 of the other. But my observations contradict this view entirely. 1 

 have traced the course of the vas deferens in more than one series of the 

 sao'ittal sections of the worm. One of these series is reproduced with- 

 out interruption on PI. XXIIT. The opening of the vas deferens of one 

 individual into the yolk-duct of the other is seen in Figs. XI. & 

 XIII. By the same series of sections, the opening of the connecting- 

 canal of the oviduct into the intestine is distinctly seen (Figs. V & 

 XIX). The vas deferens is destitute of any distinct wall of its own. 

 It seems to be merely a continuous tube-like cavity in the general 

 mesenchyma., and to collapse entirely during the winter season. 



^1 Zeller — Ueber deu Géschlechtsapparat des D/pZ. 'parado.vuni. Ztschr. f. w. Zool. Bd. 

 XLVI. 1888. p. 233. 



