CIRCULATION OF THE BLOOD 135 



organs, whilst there was yet scarcely any trace of the liver. 

 And indeed at the period when all the parts, like the heart 

 itself in the beginning, are still white, and except in the 

 veins there is no appearance of redness, you shall see 

 nothing in the seat of the liver but a shapeless collection, 

 as it were, of extravasated blood, which you might take 

 for the effects of a contusion or ruptured vein. 



But in the incubated egg there are, as it were, two 

 umbilical vessels, one from the albumen passing entire 

 through the liver, and going straight to the heart; another 

 from the yelk, ending in the vena portae; for it appears 

 that the chick, in the first instance, is entirely formed and 

 nourished by the white; but by the yelk after it has come 

 to perfection and is excluded from the shell; for this part 

 may still be found in the abdomen of the chick many days 

 after its exclusion, and is a substitute for the milk to 

 other animals. 



But these matters will be better spoken of in my ob- 

 servations on the formation of the foetus, where many 

 propositions, the following among the number, will be dis- 

 cussed: Wherefore is this part formed or perfected first, 

 that last, and of the several members, what part is the 

 cause of another? And there are many points having 

 special reference to the heart, such as wherefore does 

 it first acquire consistency, and appear to possess life, 

 motion, sense, before any other part of the body is per- 

 fected, as Aristotle says in his third book, " De partibus 

 Animalium"? And so also of the blood, wherefore does 

 it precede all the rest? And in what way does it possess 

 the vital and animal principle, and show a tendency to 

 motion, and to be impelled hither and thither, the end for 

 which the heart appears to be made? In the same way, 

 in considering the pulse, why should one kind of pulse 

 indicate death, another recovery? And so of all the other 

 kinds of pulse, what may be the cause and indication of 

 each? Likewise we must consider the reason of crises 

 and natural critical discharges; of nutrition, and especially 

 the distribution of the nutriment; and of defluxions of 

 every description. Finally, reflecting on every part of 

 medicine, physiology, pathology, semeiotics and therapeutics. 



