ON GENERATION. 409 



hoary head. For the whole body and the load of future years 

 are already traced in delicate and obscure outlines in its con- 

 stitution." 



We have already determined whether the heart were this 

 primigenial part or not ; in other words, whether Aristotle's 

 words refer to that part which, in the dissection of animals, is 

 seen sooner than all the rest, the punctum saliens, to wit, with 

 its vessels full of blood ; and we have cordially assented to an 

 answer in the affirmative. For I believe that the blood, toge- 

 ther with its immediate instruments, the umbilical vessels, by 

 which, as by roots, nutriment is attracted, and the pulsating 

 vesicles, by which this nutriment is distribiited, to maintain life 

 and growth in eveiy other part, are formed first and foremost 

 of all. For as Aristotle l has said, it is the same matter by 

 which a thing grows, and by which it is primarily constituted. 



Many, however, err in supposing that different parts of the 

 body require different kinds of matter for their nourishment. 

 As if nutrition were nothing more than the selection and at- 

 traction of fit aliment ; and in the several parts of the body to 

 be nourished, no concoction, assimilation, apposition, and trans- 

 mutation were required. This as we learn, was the opinion of 

 Anaxagoras of old : 



Who held the principles of things to be 

 Ilomceomeric : bone to be produced 

 Of small and slender bones ; the viscera 

 Of small and slender viscera ; the blood 

 Of numerous associate drops of blood. 2 



But Aristotle, 3 with the greatest propriety, observes : " Dis- 

 tinction of parts is not effected, as some think, by like being 

 carried by its nature to like; for, besides innumerable difficulties 

 belonging to this opinion in itself, it happens that each similar 

 part is severally created ; for example, the bones by themselves, 

 the nerves, the flesh, &c." But the nourishment of all parts is 

 common and homogeneous, such as we see the albumen to be 

 in the egg, not heterogeneous and composed of different parts. 

 Wherefore all we have said of the matter from which parts are 

 made, is to be stated of that by which they increase : all derive 

 nourishment from that in which they exist in potentia, though 



' Do Gen. Auiin. lib. ii, cap. 4. Lucrct. lib. i. 3 Loc. sup. cit. 



