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PHYSIOLOGY AND MORPHOLOGY OF ANIMALS. 



the mouth, and the digested food is then circulated by 

 ciliary currents through all the canals of the body (chy- 

 miferous canals), and thence directly absorbed into the 

 tissues. 



Polyp. — Another excellent example is the polyp, or 

 actinia, or sea anemone. The well-known appearance of 



Fig. 231. — Simplified figure of an actinia. 



this animal is shown in Fig. 231, and the interior struc- 

 ture in Fig. 232. Imagine a short, hollow, fleshy cyl- 

 inder (body cavity), with a disk below (the foot disk) 

 and a disk above (the mouth disk). The upper disk is 



Fig. 232.— Ideal section, vertical and horizontal, showing structure : t, ten- 

 tacles ; s, stomach ; p p, partitions. 



