PHYLUM PLATYHELMINTHES 



233 



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of the hoo! - es accordingly: when the rostellum is fully 



rt-tracted th - of the hooks are directed forwards, and may 



I'vrn meet LI litre : as the rostellum 



is protruded thfe hooks become rotated until 



their apico he directed backwards. 



Four cup-flu)p*' ( l Mi.'kcrs project slightly 



from the behind the circlet of 



hooks. 



The fax? -''it" has a jointed appear- 



ance, owii; ide up of a 



string of segii -about 



850 altogether. Tin--- . and 



shorter in front, gradually h 

 towards the posterior free extr The 



neck or part immediately following the h 

 is devoid of any trace of segmentation. The 

 two surfaces of the proglottides -are not to 

 be distinguished by any differences visible 

 to the unassisted eye ; but that side to- 

 wards which the female reproductive organs 

 are more nearly approximated is regarded as the ventral, the 

 opposite as the dorsal surface. On one border, sometimes the 

 right, sometimes the left, of each proglottis, is a little prominence, 

 the genital papilla, on which is the opening of a chamber, the 

 ycnital cloaca, into which both the male and female reproductive 

 ducts open. 



An examination of entire living, and of preserved and stained 

 Tape- Worms under the microscope shows (1) that an alimentary 



ad of 



solium, maginl 

 (After Leuckart.) \ 



FIG. 182. Transverse section of Tsenia solium. (After Shipley.) 



system is not present ; (2) that nervous and excretory systems are 

 represented ; (3) that there is a complete set of reproductive 

 organs, constructed on the same general plan as those of the 

 Liver-Fluke, present in each of the proglottides. 



The nervous system consists of two not very well-defined 

 <jaiif)lia united by a broad transverse commissure in the head ; of 



