ON GENERATION. 385 



native heat can convert into perfect blood. They deny, 

 however, that the bile can by any means be thus trans- 

 formed into blood; although the blood, they say, is readily 

 changed into bile, an event which they conceive takes place 

 in melancholic diseases, through an excess of the concocting 

 heat. 



Now, if all this were true, and there be no retrogressive move- 

 ment, viz. from black bile to bile, from bile to blood, they 

 would be brought to the dilemma of having to admit that all 

 the juices were present for the production of black bile, and 

 that this was a principal and most highly concocted nutriment. 

 It would further be imperative on them to recognize a kind of 

 twofold blood, viz. one consisting of the entire mass of fluid 

 contained in the veins, and composed of the four humours 

 aforesaid; and another consisting of the purer, more fluid 

 and spirituous portion, the fluid, which in. the stricter sense 

 they call blood, which some of them contend is contained in 

 the arteries apart from the rest, and which they then depute 

 upon sundry special offices. On their own showing, therefore, 

 the pure blood is no aliment for the body, but a certain mixed 

 fluid, or rather black bile, to which the rest of the humours 

 tend. 



Aristotle, 1 too, although he thought that the blood existed 

 as a means of nourishing the body, still believed that it was 

 composed as it were of several portions, viz. of a thicker arid 

 black portion which subsides to the bottom of the basin when 

 the blood coagulates, and this portion he held to be of an in- 

 ferior nature ; 2 " for the blood," he says, " if it be entire, is of 

 a red colour and sweet taste ; but if vitiated either by nature 

 or disease, it is blacker." He also will have it fibrous in part 

 or partly composed of fibres, which being removed, he con- 

 tinues, 3 the blood neither sets nor becomes any thicker. He 

 farther admitted a sanies in the blood : " Sanies is unconcocted 

 blood, or blood not yet completely concocted, or which is as 

 yet dilute like serum." And this part, he says, is of a 

 colder nature. The fibrous he believed to be the earthy por- 

 tion of the blood. 



According to the view of the Stagirite, therefore, the blood 



DC Part, Anim. lib. ii, cap. 3. a De Hist. Anini. lib. iii, cap. 19. 3 Ibid. 



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