PARTS OF ANIMALS, IV. v. 



up against the intestine ; this is to ensure that it and 

 its unpleasantness are kept as far as possible from the 

 body's entrance and from the sovereign and most 

 noble part. The mytis occupies a place which corre- 

 sponds exactly with that of the heart in blooded 

 creatures : which shows that it is the counterpart of 

 it.** Another proof of this is that the fluid in it is 

 sweet — that is, it has undergone concoction and is of 

 the nature of blood. 



In the Testacea the part which rules sensation 

 occupies the same place but is not so easy to pick out. 

 But this source of control should always be looked for 

 around some middle position in these creatures : in 

 stationary ones, in the midst between the part which 

 receives the food and the part where the seed or the 

 residue is emitted ; and in those which move about, 

 always midway between the right side and the left. 



In insects the part where this control is placed, as 

 was said in the first treatise,^ is situated between the 

 head and the cavity where the stomach is. In the 

 majority there is one such part, but in creatures like 

 the Centipede, that is, which are long in the body, 

 there are more than one : so if the creatures are cut 

 up they go on living. Now Nature's desire is to make 

 this part a unity in all creatures, and when she can, 

 she makes it a unity, when she cannot, a pluraUty." 

 This is clearer in some cases than in others. 



The parts connected vdih nutrition are by no means 

 alike in all insects ; indeed they exhibit great 

 differences. For instance : Some have what is 

 known as a sting inside the mouth — a sort of com- 

 bination of tongue and lips, — which possesses the 



* The heart of invertebrates escaped the notice of Aristotle. 

 * At Ilist. An. 531 b 34. « Cf. 667 b 22 if. 



■ 339 



