252 Mr. CARLISLE s Obfervations 
immediately below the places where the crofs canels are fent off. 
The alimentary canal, as it is here defcribed, is continued into the 
extreme joint, where it becomes impervious, there being no opening 
analogous toan anus. 'The individual joints have each a vaícular 
ftruéture occupying the middle part (fee fig. 4.), which is,com- 
pofed of a canal pafling from the top of the joint to the bottoms 
and from its fides are fent off a number of lateral canals nearly at 
right angles; thefe veffels contain a fluid like milk, which is alfo: 
globular, and after the death of the animal it is found coagulated.. 
When injecting this middle vafcular ftru&ure, I have, often made 
the injection pafs into the alimentary canals, by a number of very 
Ímall openings; but could never, on the contrary, inject the cen- 
tral veffels from the alimentary canals; it would feem as if there 
were a valvular apparatus fixed at the outer extremities of thofe 
radiated canals. The remaining part of the body is compofed of 
a cellular fubftance. 
The mechanifm of thofe parts of this animal which are fubfer- 
vient to its fubfiftence being now defcribed, it remains for us to 
take a general view of the manner in which the animal is nou- 
rifhed. | 
The materials compofing even the moft fimple animals not being 
permanent, but fuffering continual wafte and growing unfit for 
their purpofes, it becomes neceflary to replenifh this wafte by tak- 
ing fubftances into their, bodies, called food; and this food after- 
wards becomes a part of the folids of the animal. The food 
which Teenie feed upon, perhaps requires little change before it. 
becomes a part of the animal’s body. It is taken in by the orifice 
which we have called the mouth, and being propelled into the 
alimentary canal, it 1s made to vifit, in a general way, every part of 
the animal's body. 
The 
