32 ii. 5 — ii. 6. 



in the upper jaw the fat consists of suet. For the very fact that 

 they have horns and huckle-bones ^ shows that their composition 

 is rich in earthy matter ; for all such appurtenances are solid 

 and earthy in character. On the other hand in those hornless 

 animals that have front teeth in both jaws, and whose feet are 

 divided into toes, there is no suet, but in its place lard ; ^ and 

 this, not being of an earthy character, neither coagulates nor 

 dries up into a friable mass. 



Both lard and suet when present in moderate amount' are 

 beneficial ; for they contribute to health and strength, while 

 they are no hindrance to sensation. But when they are present 

 in great excess, they are injurious and destructive. For were 

 the whole body formed of them it would perish. For an animal 

 is an animal in virtue of its sensory part, that is in virtue of its 

 flesh, or of the substance analogous to flesh.''' But the blood, as 

 before stated, is not sensitive ; as therefore is neither lard nor 

 suet, seeing that they are nothing but concocted blood. Were 

 then the whole body composed of these substances, it would be 

 utterly without sensation. Such animals, again, as are excessively 

 fat age rapidly. For their blood is used up in forming fat, and 

 so they have but little of it left; and when there is but little 

 blood the way is already open for decay.^ For decay may be 

 said to be deficiency of blood, the scantiness of which renders 

 it liable, like all bodies of small bulk, to be injuriously affected 

 by any chance excess of heat or cold. For the same reason fat 

 animals are less prolific than others. For that part of the blood 

 which should go to form semen and seed, is used up in the 

 production of lard and suet, which are nothing but concocted 

 blood ; so that in these animals there is either no reproductive 

 excretion at all, or only a scanty amount.^ 



So much then of blood and serum, and of lard and suet. 

 Each of these has been described, and the purposes told for 

 which they severally exist. 



(Ck. 6.) The marrow also is of the nature of blood, and 

 not as some^ think the germinal force of the semen. That 

 this is the case is quite evident in very young animals. For 

 in the embryo the marrow of the bones has a blood-like 

 appearance, which is but consistent with the fact that the parts 

 are all constructed out of blood, and that it is on blood that 

 the embryo is nourished.^ But, as the young animal grows up 

 651b. 



