2 
reach the outer limits of this branch of natu- 
ral hiftory; and at the fame time, to fhew 
what egregious miftakes we are apt to commit, 
the moment we abandon the folid arguments 
furnifhed by experiments, to follow the falfe 
lights ftruck out by our weak and imperfect 
reafon, I {hall here give his imaginary account 
of this matter, as I find it in his book upon 
this fubje&t *, in his own terms, 
‘“« There are two ways,” fays he, ‘* in which 
** we obferve one thing to be made out of 
‘* another (as out of matter) both in art and 
“in nature, efpecially in the generation of 
“animals; one is, when a thing is made 
“* out of another, already in being, asa bed 
“out of wood, and a flatue out of ftone; 
“ when, for example, all the fubject-matter 
“* of the workmanthip exifts, before the work- 
‘“‘ man begins the work, or attempts to give 
“< give it any form. The other way is, when 
“the ftuff receives both being and form 
“at the fame time. As therefore the works 
‘of art are performed two ways; the one 
‘“¢ by the workman’s dividing, cutting and par- 
“‘ ing away the matter prepared for thofe ope- 
“ rations, fo as to leave behind, like a ftatuary, 
‘“‘ the figure of the thing he intends to make: 
‘the other, by the workman’s adding and 
*« moulding, as well as paring away, the mate- 
‘rials, and at the fame time tempering the 
<‘ matter itfelf, fo as to produce. like a potter, 
“the figure; which, for this reafon, may be 
“<< faid to be made, rather. than formed. In the 
“< fame manner it happens in the generation 
*¢ of animals; fome of which are formed and 
‘and transfigured out of matter already di- 
“«< sefted and encreafed for this purpofe, all the 
«© parts {pringing out ipa diftinélly, by a 
‘¢ kind of metamorphofis; and thus forming a 
See lteat animal, while other animals are made 
«piece by piece, at firft deficient both as to 
‘< fize and {hape, afterwards receive both by 
<< degrees, from the fame matter out of which 
<¢ they were originally formed. In thefe laft 
<* animals, one part is made firff, and the other 
«parts, by means of this firft, as the princi- 
«ple of the animal’s exiftence. This procefs 
<‘ of nature, we call an epigenefis, or accretion 
« of parts, on account of her forming the parts 
«¢ gradually one after another ; and this is more 
«< properly called generation than the other. 
«The generation of infeéts is performed 
<¢ after the firft manner :’” when the worm, by 
a metamorphofis, proceeds from the egg 3 OF 
the rudiments are formed out of matter in a 
ftate of putrefaGtion (by growing too dry or 
too moift) ‘ and thefe rudiments produce, as 
«< by a metamorphofis, a Caterpillar grown to 
“its full Gze, or an Aurelia, a Butterfly or 
«© a common Fly of its full fize, fo as never to 
“ grow bigger. But the more perfect fangui- 
“© ferons animals are formed by an epigenefis, 
“or a fuperaddition of parts ; and after their 
“birth, grow to a ftate of adolefcence, and 
€ arrive at their perfection. Chance or for- 
The UB °-OFO4Ki "ob MN: A DU RR GBe? of 
“* tune feems chiefly to pride in the produ@ion 
“of thofe animals, which owe their form to 
‘the power of a pre-exiftent matter; which 
“* matter is the firft caufe of their generation, 
‘ rather than any external efficient; for which 
‘“‘reafon thofe animals are more imperfect, 
‘‘ and perpetuate themfelves lefs, both as to 
‘“« number and likenefs, than fanguiferous land 
“ or water animals; which, by deriving their 
‘*‘ being from an univocal principle, (that is, 
‘* from other animals of the fame kind) keep 
*‘up an eternal fucceffion ; and the caufe of 
‘“‘ of this we attribute to nature, and a vegi- 
“« tative power. 
** Some animals, therefore, are produced of 
*‘ themfelves from matter digefted fpontane- 
** oufly, or by mere chance, as Ariftotle feems 
** to advance in the vrith book of his metaphy- 
** ficks, chap. 9. ‘Thofe animals, to wit, 
** whofe original matter can give itfelf motion, 
“« fach a motion, by accident, as the feed gives 
** itfelf in the generation of other animals. And 
‘* the fame thing happens in the generation of 
*< animals, that is obfervable in the works of 
“art; for fome things which are produced 
“€ by art, are likewife brought about by acci- 
“* dent, as health ; other things that are made by 
‘art, are never made otherwife, as a houfe. 
“« Bees, Wafps, Hornets, or Butterflies, and’ 
“‘ whatever other animals are generated by 
“* metamorphofis from a creeping infect, are 
*« faid to be the offspring of chance, and there- 
** fore never to keep up their {pecies. _ But the 
*« Lion or Cock are never produced {pontane- 
*“‘ oufly or by chance, but are the work of 
*‘ nature; wherefore they do. not require a 
*< fuitable matter, or fome other divine power, 
** fo much as a fimilar form. 
‘* In the generation by metamorphofis, ani- 
* mals are fafhioned as it were by the im- 
‘¢ preffion of a feal, or framed in a curious 
** mould, all the matter of which they confift 
** being transformed ; whereas the animal which 
‘* is produced by way of epigenefis, or accre- 
‘* tion, at once attracts, prepares, digefts, and 
‘* makes ufe of the ready matter; it at once 
“* orows and acquires its form. . In the former, 
« the plaftic power divides the fame fimilar 
‘“< matter, arranges it when divided, and re- 
“* duces it into limbs; from fimilar making it 
<* diffimilar, or forming diffimilar organs with 
<a fimilar fubftance. Butin the latter, whilft 
“« it produces in order different parts, and thofe 
‘‘ parts differently difpofed, it requires and 
«* makes different fubftances ; and fubftances are 
“-yarioufly difpofed, the better to fuit the dif- 
‘* ferent parts that are to be generated.” 
This is the doctrine of Harvey; and this 
his differtation. contains almoft as. many errors 
as words. ‘This may appear furprifing in one 
fo well verfed in enquiries of this kind, where . 
truth can only be afcertained by experiment : 
notwithftanding all his errors, we muft do his 
great merit in other refpects juftice; his dili- 
gence in ftudying nature was very great, and 
® Lib. de Gen. An. Exerc. XLV, 
he 
