262 



ZOOLOGY 



SECT. 



animals. In this case the hooked embryo develops into a large 

 mother-cyst, from the interior of which daughter-cysts are budded off 

 (Fig. 209). Eventually from the walls of these daughter-cysts there 



I-'K,. L'Oii. C'yst of Tsenia echinococcus with the developing daughter-cysts and scolices. 



(After Leuekart.) 



are formed numerous tape- worm heads, or scolices (Figs. 210 and 211) 

 which, when fully formed, assume the appearance of cysticercoids 

 without the caudal vesicle. These are readily detached, and, should 

 the organ in which the cyst has been developed be devoured by a 

 Dog which is the final host of the parasite some of these scolices 



become attached to the wall 

 of the intestine and de- 

 velop into the as compared 

 with the size of the cyst, and 

 as compared with other tape- 

 worms very small adult 

 Tccnia echinococcus. The eggs 



Fi<;. 21U. Scolices of T. echinococcus. 



(After Cobbold.) 



Fir;. 211. Separate scolex of 

 T. echinococcus. (After 

 Cobbold.) 



which the latter produces, passing out with the fieces of the Dog, 

 may be taken into the digestive canal of Man or of one of the 

 domestic animals, and the minute embryos escaping reach some 

 organ, such as the liver or lung, in which they are capable of 

 developing into a comparatively enormous cyst. 



