EXAMINATION OF HELMINTHES 



147 



Kipe segments from the hinder middle portion of Dibothrio- 

 cephalus, if examined in the same manner, reveal other conditions. 

 The proglottide is divided longitudinally into three fields, which differ 

 in colour and in degree of transparency. The two lateral spaces are 

 opaque and yellowish-brown in appearance, owing to the presence 

 near the surface of innumerable little granules the yolk-gland 

 follicles. The central field is more transparent and contains an 

 apparently branched or rosette-shaped organ, in front of which is 

 a rounded structure of whitish colour. The latter is the cirrhus- 

 pouch, while the rosette-like organ is the uterus, arranged, as in 

 Fasciola hepatica, in transverse folds, which are here filled with 

 brownish eggs. The loops are approxi- 

 mated in various degrees, enclosing wider 

 or narrower fields, according to the state 

 of contraction of the segments. End 

 proglottides sometimes have the uterus 

 partially or completely empty. This is 

 owing to the fact that the uterus is fur- 

 nished with an opening through which the 

 eggs escape, while the sexual glands be- 

 come atrophied and cease to form eggs. 



The terminal segments of tapeworms, 

 as is well known, are released, either 

 singly or in numbers, and are conveyed 

 to the exterior in the faeces of their host. 

 If this has not as yet taken place, it is 

 certain that the specimen under examin- 

 ation is comparatively young. In such 

 a case, the terminal proglottides of 

 the greater number of, cestode species, 

 if not all, will be smaller in size than in 

 the adult worm, and will be deficient in 

 sexual organs. 



The student should be on the watch for abnormalities of structure. 

 In Bothriocephales these are usually due to the interpolation of wedge- 

 shaped joints, though fenestration of single or of successive joints 

 is also frequent, as also the absence or incomplete formation of the 

 line of demarcation between the joints. Duplication of the genital 

 pores, as well as of the genital glands ; reversal of the genitals ; 

 bifurcation of the segmented body, and duplication of the entire 

 worm, which then assumes a triagonal form, are also malformations 

 which are not infrequently met with. 



Before preparing fresh Cestodes for permanent preservation, a 

 ripe proglottide should be detached and teazed out on a glass slide 



FIG. 68. Ripe proglottides of 

 Tcenia solium (left) and T. 

 saginata (right), showing the de- 

 velopment of the uterus in the 

 large-hooked Tsenise of mammals. 

 2:1. 



