ON GENERATION. 373 



animals, is confirmed and made manifest by all that passes in 

 the egg, viz. : that all the parts are not formed at once and 

 together, but in succession, one after another ; and that there 

 first exists a particular genital particle, in virtue of which, as 

 from a beginning, all the other parts proceed. As in the seeds 

 of plants, in beans and acorns, to quote particular instances, 

 we see the gemmula or apex, protruding, the commencement 

 of the entire prospective herb or tree. " And this particle is 

 like a child emancipated, placed independently, a principle ex- 

 isting of itself, from whence the series of members is subse- 

 quently thrown out, and to which belongs all that is to con- 

 duce to the perfection of the future animal." l Since, there- 

 fore, " No part engenders itself, but, after it is engendered, 

 concurs in its own growth, it is indispensable that the part first 

 arise which contains within itself the principle of increase ; for 

 whether it be a plant or an animal, still has it within itself the 

 power of vegetation or nutrition ;" 3 and at the same time 

 distinguishes and fashions each particular part in its several 

 order ; and hence, in this same primogenate particle, there is 

 a primary vital principle inherent, which is the author and 

 original of sense and motion, and every manifestation of life. 



That, therefore, is the principal particle whence vital 

 spirit and native heat accrue to all other parts, in which the 

 calidum innatum sive implantatum of physicians first shows it- 

 self, and the household deity or perennial fire is maintained; 

 whence life proceeds to the body in general, and to each of its 

 parts in particular; whence nourishment, growth, aid, and 

 solace flow ; lastly, where life first begins in the being that is 

 born, and last fails in that which dies. 



All this is certainly true as regards the first engendered part, 

 and appears manifestly in the formation of the chick from the 

 egg. I am therefore of opinion that we are to reject the views 

 of certain physicians, indifferent philosophers, who will have it 

 that three principal and primogenate parts arise together, viz. : 

 the brain, the heart, and the liver; neither can I agree with 

 Aristotle himself, who maintains that the heart is the first 

 engendered and animated part ; for I think that the privilege 

 of priority belongs to the blood alone ; the blood being that 



1 De Gen. Aniin. lib. ii, cap. i. 2 Ibid. cap. 4. 



