342 PHYSIOLOGY AND MORPHOLOGY OF ANIMALS. 



sheath, a long, slender, slightly curved rod, sharp and 

 enameled at the point. These prismatic pieces with 

 their sharp teeth are worked by powerful muscles, so 

 as to move radially to and from the center. The 

 food is taken by curious nipping appendages (pedi- 

 cellariae) and handed on to the mouth and divided 

 and chewed by the lantern apparatus. The stomach is 

 immediately above the lantern ; the intestine is much 

 convoluted, and emerges by opening in the center of the 

 radiated upper surface of the animal. 



CCELENTERATES. 



Thus far we have found intestinal as well as stom- 

 achal digestion. The food preparation is carried to 

 the condition of chyle. In all such cases there is a blood 

 system distinct from the digestive system, and into 

 which the chyle is absorbed, to become afterward 

 changed into blood. In all animals spoken of thus far 

 blood and digested food are distinct from one another. 

 The digested food is absorbed and changed into blood 

 (sanguined). But now we find a great change in this re- 

 gard. In the ccelenterates, and below, there is no longer 

 any intestine as distinct from the stomach. The diges- 

 tion goes only as far as chyme-making. There is no 

 longer any distinction between the digestive system and 

 the blood system, nor between digested food and blood. 

 The digested food is the only nutrient fluid. We take 

 as an excellent example of ccelenterates the 



Medusa, or Jellyfish, or Sea- Blubber. —These 

 beautiful, almost transparent, saucerlike or bell-shaped 

 animals (Fig. 229), with their long trailing tentacles and 

 graceful movements, are the delight of the intelligent 

 seashore visitor, and especially of the naturalist. 



How do they take their food? The movement of 

 their tentacles is far too slow for this purpose. They 



