374 ON GENERATION. 



which is first seen of the newly engendered being, not only in 

 the chick in ovo, but in the embryo of every animal whatso- 

 ever, as shall plainly be made to appear at a later stage of 

 our inquiry. 



There appears at first, I say, a red-coloured pulsating point 

 or vesicle, with lines or canals extending from it, containing 

 blood in their interior, and, in so far as we are enabled to per- 

 ceive from the most careful examination, the blood is produced 

 before the punctum saliens is formed, and is farther endowed 

 with vital heat before it is put in motion by a pulse ; so that 

 as pulsation commences in it and from it, so, in the last struggle 

 of mortal agony, does motion also end there. I have indeed ascer- 

 tained by numerous experiments instituted upon the egg, as well 

 as upon other subjects, that the blood is the element of the body 

 in which, so long as the vital heat has not entirely departed, 

 the power of returning to life is continued. 



And since the pulsating vesicle and the sanguineous tubes 

 extending thence are visible before anything else, I hold it as 

 consonant with reason to believe that the blood is prior to its 

 receptacles, the thing contained, to wit, to its container, inas- 

 much as this is made subservient to that. The vascular rami- 

 fications and the veins, therefore, after these the pulsating vesicle, 

 and, finally, the heart, as being every one of them organs des- 

 tined to receive and contain the blood, are, in all likelihood, 

 constructed for the express purpose of impelling and distributing 

 it, and the blood is, consequently, the principal portion of the 

 body. 



This conclusion is favoured by numerous observations ; par- 

 ticularly by the fact that some animals, and these red-blooded, 

 too, live for long periods without any pulse ; some even lie con- 

 cealed through the whole winter, and yet escape alive, though 

 their heart had ceased from motion of every kind, and their 

 lungs no longer played ; they had lain in fact like those who 

 lie half dead in a state of asphyxia from syncope, leipothymia, 

 or the hysterical passion. 



Emboldened by what I have observed both in studying the 

 egg, and whilst engaged in the dissection of living animals, I 

 maintain, against Aristotle, that the blood is the prime part 

 that is engendered, and the heart the mere organ destined 

 for its circulation. The function of the heart is the pro- 



