ON GENERATION. 3/9 



heat and colour from the blood ; the blood is in no wise derived 

 from the liver. 



From what has now been said, then, it appears that the 

 blood is the first engendered part, whence the living principle 

 in the first instance gleams forth, and from which the first ani- 

 mated particle of the embryo is formed ; that it is the source and 

 origin of all other parts, both similar and dissimilar, which 

 thence obtain their vital heat and become subservient to it in its 

 duties. But the heart is contrived for the sole purpose of 

 ministering between the veins and the arteries of receiving 

 blood from the veins, and, by its ceaseless contractions, of pro- 

 pelling it to all parts of the body through the arteries. 



This fact is made particularly striking, when we find that 

 neither is there a heart found in every animal, neither does it 

 necessarily and in every instance pulsate at all times where 

 it is encountered ; the blood, however, or a fluid which stands 

 in lieu of it, is never wanting. 



EXERCISE THE FIFTY-SECOND. 



Of the blood as prime element in the body. 



IT is unquestionable, then, and obvious to sense, that the 

 blood is the first formed, and therefore the genital part of the 

 embryo, and that it has all the attributes which have been 

 ascribed to it in the -preceding exercise. It is both the author 

 and preserver of the body ; it is the principal element more- 

 over, and that in which the vital principle (anima) has its 

 dwelling-place. Because, as already said, before there is any 

 particle of the body obvious to sight, the blood is already ex- 

 tant, has already increased in quantity, " and palpitates within 

 the veins," as Aristotle expresses it, 1 "being moved hither and 

 thither, and being the only humour that is distributed to every 

 part of the animal body. The blood, moreover, is that alone 

 which lives and is possessed of heat whilst life continues." 



And further, from its various motions in acceleration or re- 



1 Hist. Anim. lib. iii, cap. 19. 



