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.
