PARTS OF ANIMALS, III. m.-iv. 



heart must of necessity be situated in the front place 

 of all, both the larynx and the Λvindpipe, which lead 

 to the lung and the heart, must of necessity be 

 situated in front of the oesophagus which leads merely 

 to the stomach. Speaking generally, unless some 

 greater object interferes, that which is better and 

 more honourable tends to be above rather than below, 

 in front rather than at the back, and on the right side 

 rather than on the left. 



We have ηολν spoken of the neck, the oeso- 

 phagus, and the winc^pipe, and our next topic is the 

 viscera. 



IV. Only blooded atiimals have viscera. " Some, but internal 

 not all, have a complete set of them. As no blood- blooded 

 less animals have them, Democritus must have been animaia 

 wrong in his ideas on this point, if he really supposed 

 that the viscera in bloodless creatures are invisible 

 owing to the smallness of the creatures themselves. 

 Against this we can put the fact that the heart and 

 the liver are visible in blooded animals as soon as they 

 are formed at all, that is, when they are quite small : 

 in eggs they are visible, just about the size of a point, 

 sometimes as early as the third day, and very small 

 ones are visible in aborted embryos. Further, just 

 as each animal is equipped Λvith those external parts 

 which are necessary to it for its manner of life and its 

 motion, and no tΛvo animals require exactly the same 

 ones, so it is with the internal parts : they vary in the 

 various animals. 



Viscera, then, are peculiar to the blooded animals, Heart, 

 and that is why each one of the viscera is formed of 

 blood-like material. This is clearly to be seen in the 

 new-born offspring of blooded animals ; in them the 

 viscera are more blood-like, and at their largest in 



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