ZOOLOGY 



The terminal proglottis breaks off from the rest of the 

 Tapeworm owing to the contraction of its muscles, its rupture 

 affects the transverse excretory duct of the segment in front, 

 which is put into communication with the outer world, and thus 

 forms the new terminal vesicle, which opens to the exterior. 



The ripe proglottis passes out of the alimentary canal of 

 its host, and the eggs with which it is crowded escape by the 

 rupture of its walls. In some species the free proglottides. 



Fio. 68. — Development of Taenia. From Leuckart. 

 A, Oyslicercus boms, from beef. Natural D. Stages in the development of the 



B. Invaginated head of Cysticercus before 



the formation of the suckers. 

 X 20. 



C. Invaginated head of Cysticercus cellu- 



losae, showing the bent head, x 30. 



brood capsules in EchivAicoccnis, 

 The thickening in the parenchyma of 



the bladder. 

 Subsequent formation of a cavity in it. 

 Development of the suckers. 

 A capsule with one head invaginated. 



e. A capsule with two heads, x 90. 



after they have left their host, retain a considerable power of 

 movement, and crawl over blades of grass, etc. In this way 

 their ova are disseminated, and stand a better chance of 

 being eaten by their second host, in whose body alone they 

 can develop. Some of them succeed in making their way, 

 either by means of the food or water, into the stomach or 



