PARTS OF ANIMALS, III. iv.-v. 



the only part in the whole body — which cannot 

 withstand any serious affection. This is readily 

 understood : the other parts depend upon the heart, 

 and when this source itself is ailing, there is no place 

 Λvhence they can obtain succour. A proof that the 

 heart cannot put up with any affection is this : Never 

 has the heart in a sacrificial victim been observed 

 to be affected in the way that the other viscera 

 sometimes are. Very often the kidneys are found 

 to be full of stones, growths, and small abscesses ; 

 so is the liver, and the lung, and especially the 

 spleen. Many other affections are observed in 

 these organs ; but in the lung they occur least 

 often in that portion which is nearest the windpipe, 

 and in the liver in that portion Λvhich is nearest its 

 junction Avith the Great Blood-vessel. This is readily 

 understood : those are the places Avhere they are 

 most closely in communication with the heart. 

 Those animals, however, which die as the result 

 of disease, and affections such as I have mentioned, 

 when cut open are seen to have diseased affections 

 of the heart. 



We have now spoken of the heart : we have said 

 Avhat its nature is, what purpose it serves, and why it 

 is present ; and that will suffice. 



V. I suppose that the next subject for us to discuss Blood- 

 is the Blood-vessels, that is, the Great Blood-vessel ^^^^^ ^' 

 and the Aorta. It is these into which the blood 

 goes first after it leaves the heart, and the other 

 blood-vessels are merely branches from these. We 

 have already said that these blood-vessels are present 

 for the sake of the blood : fluid substances always 

 need a receptacle, and the blood-vessels generally 

 are the receptacles which hold the blood. We may 



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