NO. 2258 



TAENIOID CESTODES OF DOGS AND CATS— HALL. 



35 



contact with the vitellarium. The vagina has usually a slightly 

 sinuous course in the lateral field of the segment, but after crossing 

 the longitudinal excretory canals it extends medially in a rather 

 straight or but slightly curved course and either barely clears the 

 anterior margin of the nearest ovary or crosses the anterior portion 

 of this ovar}^, a quite unusual and distinctive feature. In gravid 

 segments (fig. 39) the me- 

 dian uterine stem bears on 

 each side 20 to 25 lateral 

 branches, which in turn send 

 out numerous secondary 

 branches which frequently 

 fuse. The eggs are oval, 30 

 to 34 ;;. long by 24 to 28 ;j. 

 wide. 



Hosts. — Primary : Canis 

 familiaris. Secondary : Ovh 

 aries, Capra hircus. 



Location. — In small intes- 

 tine of primary host. Em- 

 bedded in the heart, volun- 

 tary muscles, esophagus, 

 lungs, walls of stomach ( ? ) , 

 and kidneys (?) of secondary 

 hosts. 



Localities. — England, 

 France. Germany, Algeria, 

 German Southwest Africa, 

 Xew Zealand, and the United 

 States. 



Life history. — Eggs devel- 

 oped by the adult worm in 

 the intestine of the primary 

 host pass out and are in- 

 gested in contaminated food 

 or water by the secondary 

 host. In the digestive tract 

 of the secondary host the 

 embryos escape and bore 

 their way into the muscles and other suitable portions of the host's 

 anatomy and finally come to rest and develop to the bladderworm 

 stage, called Cysticerciis ovis. On the ingestion of these larvae by 

 the primary host the head of the bladderworm develops segments 

 and forms the strobilate tapeworm. 



The evidence to the effect that the larvae of this parasite are widely 

 distributed over the world and that they have been overlooked in 



^mmmi 



«=2S,\ 





U*//. iM i^iTv, vV) Y\\ 



imm. 



FlG.39.— TaENU OVIS. GEAVID SEGMENT. AFTER RAN- 

 SOM, 1913. 



