VERMES 



"5 



or cyst is formed in the organ, and the embryo develops into 

 what is technically called a c\ sticercus, or popularly a bladder 

 worm (Fig. 102). It consists of a scolex, to which a saclike 



FlG. 105. Scolices of various tapeworms sometimes found in man. i, Tama solium, the 

 pork tapeworm ; 2, Tceiua saginata ( medioi arte Hat a ), the beef tapeworm ; 3, Bothriocephalus 

 lotus, the fish tapeworm, two views; all enlarged. (Alter Leuckart, from Hatschek's 

 rbuch.) 



enlargement is attached. In its first host the worm never 

 advances beyond this immature condition ; but when the first 

 host is eaten by the second and final host, the cysticercus is set 

 free in the intestine, its 



scolex becomes attached 

 to the wall, the bladder- 

 like enlargement is lost, 

 and proglottides begin to 

 form. The embryonic 

 stages occur in both 

 the vertebrates and the 

 invertebrates, while the 

 adults exist in verte- 

 brates which feed on 

 the first host ; the cys- 



FlG, 106. Ripe proglottides of the two common tape- 

 worms, showing in each the branched uterus as it 

 tlCerCUS OI a tapeworm appears when filled with eggs. 1, Taenia solium ; 



2, Tania saginata. (After Leuckart, from Hatschek's 

 Lehrbuch.) 



of the cat, for example, 

 is found in the mouse. 



The Cestoda are of particular interest because there are some 

 which occasionally occur in man. Of these the largest, Bothrio- 

 cephalic la tits, is apparently confined to Europe, especially to 

 parts of Russia, Switzerland, and southern France. The cys- 

 ticercus lives in various fishes, and infection is the result of 



