PARTS OF ANIMALS, III. ix. 



motion they are bound to make their way upwards 

 before the ones on the left. Thus people raise the 

 right eyebrow more than the left, and it is more 

 arched. A result of this drawing up of the right 

 kidney is that in all animals the liver, which is on the 

 right side of the body, is in contact with it. 



The kidneys contain more fat than any other of the Fat in 

 viscera. This is partly a necessary consequence upon '^^*^"''y* 

 the percolation of the residue through the kidneys : 

 in other words, the blood which gets left behind there 

 is easy of concoction because it is pure, and when 

 blood undergoes complete concoction the final pro- 

 ducts are lard and suet. (A parallel is to be found in 

 the case of solid substances which have undergone 

 combustion : e.g. a certain amount of fire gets left 

 behind in ash. So, in fluid substances which have 

 undergone concoction : some portion of the heat 

 which has been generated remains behind. That is 

 Λvhy oily substances are light and come to the top of 

 fluids.) This fat is not formed actually in the kidneys 

 themselves, because they are so dense : it collects 

 outside them. In some it has the form of lard, in 

 others the form of suet, according to the character of 

 the animal. (The difference between the two has 

 been explained already in another connexion.) " 



This formation of lard, then, about the kidneys is 

 the necessary consequence upon the conditions which 

 necessarily obtain in animals that possess kidneys. 

 But there is another reason for its formation, and that 

 is, on purpose to safeguard the kidneys themselves 

 and to preserve their natural heat. The kidneys are 

 the outermost of all the viscera, and therefore they 

 need more warmth. Whereas the back is liberally 

 supphed with flesh, which enables it to act as a 



275 



