PARTS OF ANIMALS, II. iv.-v. 



not taken out, it does congeal, as moist earth does 

 under the influence of cold : the cold expels the heat 

 and makes the fluid evaporate, as has been said 

 before ; so it is due to the solidifying effect of 

 the cold, and not of the hot, that what remains 

 becomes congealed. And while it is in the body the 

 blood is fluid on account of the heat which is there. 



There are many points both in regard to the tem- 

 perament of animals and their power of sensation 

 which are controlled by the character of the blood. 

 This is what we should expect : for the blood is the 

 material " of which the whole body consists — material 

 in the case of living creatures being nourishment, and 

 blood is the final form which the nourishment assumes. 

 For this reason a great deal depends upon whether 

 the blood be hot, cold, thin, thick, muddy, or clear. 

 Serum is the watery part of blood ; and it is watery 

 either because it has not yet undergone concoction or 

 because it has been already corrupted ; consequently 

 some of the serum is the result of a necessary process, 

 and some is there for the purpose of producing blood. 



V. The difference between lard and suet ^ is parallel i-ard and 

 to a difference in the blood. They both consist of ^^^ 

 blood that has been concocted as the result of plentiful . 

 nourishment ; that is, the surplus blood that is not 

 used up to nourish the fleshy parts of the animal, but 

 is well concocted and well nourished. (This point 

 is proved by their greasiness, for grease in fluids is 

 a combination of Air and Fire.) This explains 

 why there is no lard or suet in any of the bloodless 

 animals. And among the others, those whose blood 

 is denser tend to contain suet rather than lard. Suet 



due to varying proportions of unsaturated triglycerides and 

 the lengths of the carbon chains. 



141 



