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 Tania 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 crassicollisof 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.” + 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. 377. 
f Dr Carpenter. 
