PARTS OF ANIMALS, IV. v. 



and the animals on the other. Towards the animals, 

 because some of them detach themselves and fasten 

 upon their food, and are sensible of objects that come 

 up against them ; and also because they make use 

 of the roughness of their body for self-preservation. 

 Towards the plants, because they are incomplete, 

 and quickly attach themselves to rocks ; and further, 

 because they have no residue that can be seen, 

 though they have a mouth. The group of Starfish 

 resembles these creatures ; Starfish too fasten on to 

 their food, and by doing this to oysters suck large 

 numbers of them dry. But Starfish also resemble 

 those unattached creatures of which we spoke, the 

 Cephalopods and the Crustacea. The same may be 

 said of the Testacea. 



The parts connected with nutrition are such as I 

 have now described. These must of necessity be 

 present in all animals. But there is yet another part 

 which every animal must have. These creatures must 

 have some part which is analogous to the parts 

 which in blooded animals are connected with the 

 control of sensation. In the Cephalopods this con- 

 sists of a fluid contained in a membrane, through 

 which the gullet extends towards the stomach. It is 

 attached to the body rather towards the upper " side. 

 Some call it the myt'is. An organ just like this, also 

 called the mytis, is present in the Crustacea. This 

 part is fluid and corporeal at the same time. The 

 gullet, as I said, extends through the middle of it. 

 If the gullet had been placed between the mytis and 

 the dorsal side, the gullet ΛνοηΗ not have been able 

 to distend sufficiently when the food enters, owing to 

 the hardness of the back. The intestine is placed up 

 against the outer surface of the mytis, and the ink-bag 



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