INTESTINAL WORMS; 



123 



The sexual character of their posterior segments was com- 

 pletely developed, a great number of ova in a state of 

 maturity being contained in them. Some individuals had 

 already separated their last joints in a perfectly mature 

 state. 



" In the Cysticercus pisiformis thus elongated, I recog- 

 nise the Tcenia serrata of the dog. The extremity of the 

 head, the form of the segments, the nature of the organs 

 of generation, and, above all, of the mature ova of this 

 worm, agreed exactly with the same parts of the Tcenia 

 serrata. There was no longer therefore any doubt that 

 the Cysticercus pisiformis of the hare and rabbit is to the 

 Tcenia serrata of the dog what the Cysticercus fasciolaris of 

 the mouse and rat is to the Tcenia crassicollis of the cat. 



" The Tcenia serrata is rarely found in watch-dogs or 

 house-dogs, but more commonly in coursing-dogs ; which 

 is easily explained by the fact, that the latter frequently 

 devour the intestines of hares and rabbits captured in the 

 chase, and consequently swallow the Cysticercus more fre- 

 quently than other dogs."" 



From these and other carefully conducted observations, 

 it seems established that the Cystoid worms are only the 

 Cestoids imperfectly developed, " their bodies being en- 

 cysted in the caudal segment, and this being, as it were, 

 dropsically distended." t The development of the embryo 

 into the Cestoid state, or its arrest in the Cystoid, appears 

 to depend on the nidus in which it is lodged, and this on 

 the habits of the involuntary nurse ; if the embryo lodge 

 in a herbivorous animal, it becomes only a Cystoid worm, 



* Ann. des Sci. Nat. 3d ser., xvii. 877. 



f Dr Carpenter. , 



