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way becomes immediately mingled with the blood, where it 

 might receive digestion and perfection from the heat, and 

 serve for the nutrition of all the parts ? For the heart itself 

 can be accounted of higher importance than other parts ; can 

 be termed the source of heat and of life, upon no other 

 grounds than as it contains a larger quantity of blood in its 

 cavities, where, as Aristotle says, the blood is not contained in 

 veins as it is in other parts, but in an ample sinus and cistern, 

 as it were. And that the thing is so in fact, I find an argu- 

 ment in the distribution of innumerable arteries and veins to 

 the intestines, more than to any other part of the body, in 

 the same way as the uterus abounds with blood-vessels during 

 the period of pregnancy. For nature never acts inconsiderately. 

 In all the red-blooded animals, consequently, which require 

 [abundant] nourishment, we find a copious distribution of 

 mesenteric vessels ; but lacteal veins we discover in but a few, 

 and even in these not constantly. Wherefore, if we are to 

 judge of the uses of parts as we meet with them in general 

 and in the greater number of animals, beyond all doubt those 

 filaments of a white colour, and very like the fibres of a 

 spider's web, are not instituted for the purpose of transport- 

 ing nourishment, neither is the fluid they contain to be desig- 

 nated by the name of chyle ; the mesenteric vessels are rather 

 destined to the duty in question. Because, of that whence an 

 animal is constituted, by that must it necessarily grow, and by 

 that consequently be nourished; for the nutritive and augmenta- 

 tive faculties, or nutrition and growth, are essentially the same. 

 An animal, therefore, naturally grows in the same manner as 

 it receives immediate nutriment from the first. Now it is a 

 most certain fact (as I have shown elsewhere) that the embryos 

 of all red-blooded animals are nourished by means of the um- 

 bilical vessels from the mother, and this in virtue of the circula- 

 tion of the blood. They are not nourished, however, immediately 

 by the blood, as many have imagined, but after the manner of 

 the chick in ovo, which is first nourished by the albumen, and 

 then by the vitellus, which is finally drawn into and included 

 within the abdomen of the chick. All the umbilical vessels, 

 however, are inserted into the liver, or at all events pass 

 through it, even in those animals whose umbilical vessels enter 

 the vena porta?, as in the chick, in which the vessels proceeding 



