Page:The Works of William Harvey (part 1 of 2).djvu/442

342 to the effect, as some parts produced by epigenesis are poste- rior in order to other parts, and are different from antecedent parts, as effects differ; so does it seem probable that efficients also vary : from things that produce different operations, dif- ferent motions likewise proceed. Thus physicians in their physiologies assign certain organs as the agents of chylification, others of sanguification, others of generation, &c. ; and anato- mists speak of the ossific, carnific, and neurific faculties, which they conceive produce bones, flesh, and nerves.

But in the generation of the chick, of several actions differ- ing not a little from one another, it is certain that the efficient causes must also differ ; those that present themselves to us as accidental efficients of generation must nevertheless be neces- sary, seeing, that unless they are associated or intervene, no- thing is effected ; those, to wit, are rightly held " efficients " which, whilst they remove external hinderances, either cherish the conception, or stimulate and turn mere potentiality into positive action. Under this head we should arrange incuba- tion, the proper temperature of the air and the place, the spring season, the approach of the sun in the circle of the zodiac ; in like manner the preparing causes which lead the vitellus to rise, make the macula to dilate, and the fluids in the egg to liquefy, are all properly held " efficients."

Further, to the number of efficient causes are to be rec- koned the generative and architectonic faculties, styled parts by Fabricius, viz., the immutative, the concoctive, the formative, the augmentative, as also the effective causes of certain acci- dentals, viz., that which constitutes the pullet male or female, like the father or the mother, taking after the form of the first or last male having connection with the mother; that too whence the offspring is an animal ; whether perfect or defective ; robust and healthy, or diseased ; longer or shorter lived ; keep- ing up the characters of the race or degenerating from them ; a monster, an hybrid, &c.

Lastly, when we were discussing the efficient causes of the foetus, we were not inattentive to its admirable structure, to the functions and uses of all its parts and members ; neither did we overlook the foresight, the art, the intelligence, the divine inspiration with which all things were ordained and skilfully continued for the ends of life. It is not enough that