PARTS OF ANIMALS, III. ix.-x. 



the sheep off. The disease makes its way directly to 

 the heart through the Aorta and the Great Blood- 

 vessel, since there are continuous passages leading 

 from these to the kidneys. 



We have now spoken of the heart and the lung ; 

 and also of the liver, the spleen and the kidneys. 

 X. These two sets of viscera are separated from Diaphragm. 

 each other by the diazoma, which some call the 

 phrenes (diaphragm). This divides off the heart and 

 the lung. In blooded animals it is called j)hrenes, as 

 I have said. All blooded creatures have one, just as 

 they all have heart and liver. The reason for this 

 is that the diaphragm serves to divide the part 

 round the stomach from the part round the heart, 

 to ensure that the source of the sensory Soul may be 

 unaffected, and not be quickly overwhelmed by the 

 exhalation that comes up from the food when it is 

 eaten and by the amount of heat introduced into the 

 system. For this purpose, then. Nature made the 

 division, and constructed the phrenes to be, as it were, 

 a partition-wall and a fence ; and thus, in those 

 creatures where it is possible to divide the upper 

 from the lower, she divided off the nobler parts 

 from the less noble ones ; for it is the upper which 

 is " better," that ybr the sake of which the lower ex-' 

 ists, while the lower is " necessary," existing ybr the 

 sake of the upper, by acting as a receptacle for the 

 food. 



Towards the ribs the diaphragm is fleshier and 

 stronger, while in the middle it is more like a mem- 

 brane : this makes it more serviceable as regards 

 strength and extensibility. An indication to show 

 why there are, as it were, " suckers," to keep off the 

 heat which comes up from below, is provided by 



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