CESTODA. 



337 



Bothriocephalus Brems. Segmented body. Head with two pits, without 

 hooks. The genital openings are on the middle of the ventral surface. The 

 young stage usually in fishes. B. latus Brems., the largest of the tape-worms 

 parasitic in man, twenty-four to thirty feet in length, principally found in 

 Kussici, Poland, Switzerland, and South France. The sexually mature segments 

 are broader than they are long (about 10 12 mm. broad and 3 5 mm. long). 

 They do not become detached singly, but in groups (fig. 274). The segments 

 of the hindermost portion of the body are, how- 

 ever, narrower and longer. The head is club- 

 shaped, and is provided with two slit-like pits. 

 The cortical parts of the lateral regions of the 

 body contain a number of round masses of 

 granules, the yolJt-glands (fig. 275, Dsf), the 

 contents of which are poured into the shell 

 glands (coiled glands) through the so-called 

 yellow ducts. 



The genital openings lie close together, one 

 behind the other, in the midst of the segment 

 (fig. 275, #). The anterior and larger belongs to 

 the male generative apparatus, and leads into the muscular terminal portion 

 of the vas deferens, which is enclosed in the cirrus sheath and can be eva- 

 ginated as the cirrus (fig. 275, Cb~). The vas deferens just before its entrance 

 into the cirrus pouch is dilated (fig. 275 5) to form a large muscular swelling 

 (the vesicula seminalis ?). It then becomes coiled, and passes in the direction 



FIG. 274 J. Larva of a Bofhrio- 

 cephalusfrom the Smelt (after 

 R. Leuckart). 



FIG. 275. Geaerattve organs of a sexually mature proglottis of SothrioeepAaltu latui (after 

 Sommer and a. Leuckarl) ; a, from the ventral surface, 5, from the dorsal surface. Ov 

 and P, ovary ; Ut, uterus ; Sd, shell gland ; Dst, vitellarium (yolk gland) ; Va, vagina with 

 opening ; T, testis ; Cb, pouch of the cirrus ; Vd, vas deferens. 



of the long axis of the segment on the dorsal surface and divides into two 

 side branches. These receive the efferent canals of the delicate testicular 

 sacs, which occupy the lateral parts of the middle layer (T). The female 

 genital opening (fig. 275 a) leads into a vagina ( Va) situated behind the pouch 

 of the cirrus, and frequently filled with semen. This vagina runs as a tolerably 



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