GENERATION. 



in every feiifibl'' point of matter ; it is afiilled by heat. 

 There is a power, in every point of vegetable matter, to pro- 

 duce filaments, from tvhicii niicrofcopic animalcu'.a may be 

 formed. A real generating caufe cxifts in nature. The 

 expanfive force is increafed, and the refillance diminiihed, 

 when matter is elevated to a ilate of vitality. This is 

 eiTccled bv the devclopement of the active principles ; it 

 returns again to a vegetable nature, when the contrai-/ 

 caufes obtain. He does not; however, admit of equivocal 

 generation, but conceives it neceflary, that the feminal fluids, 

 both of the male and female, charadlerized by their pecuhar 

 properties, fhould be prefent. 



In this hypothefis the power of the femen is not neglefted, 

 nor IS any attradlion er fortuitous concourfe of atoms admit- 

 ted. But the experiments on intufion animalcula are em- 

 ployed to authorize conclufions, v^hich cannot be very ealily 

 admitted. We find a great difficulty in admitting how any 

 blind force, not regulated by defign, can form animals de- 

 figi'.jd for certain purpofes, and fit to fill their place in the 

 chLiin of beings. Hence we fmd that thefe animalcula are 

 not produced when the experiments are fo'itondudled as to 

 remove all pofiibility of the introduction of ova from without. 

 The experiments of Spallanzani clearly prove this point. 



The fyftem of epigenefis met with an able defender in C. 

 F. Wolf : fee his 1 heoriaGencrationis, Halle, 1759, 4to. He 

 explains the mode of growth, and the formation of parts in 

 animals and vegetables, by the aftion of a power which he 

 calls I'.'j- ejf.ntiaTts, without any mould or model. This power, 

 together with the fixation or coagulation (foli defcentia) of 

 juices, accomplices the whole work of formation. The heat 

 of the air in plants, and the heart in animals, are acceflbry 

 caufes of generation. The primordia of animals are glo- 

 bules, which cannot be reduced into fmaller component parts; 

 neither arteries, veins, nor heart exift in the egg at 24 hours. 

 The vis eflbntialis, different from the power of the heart, now 

 begins to aft, and, in the globular matter of the area umbi- 

 licalis, forms grooves, which gradually grow red, andconftitute 

 vefTtls. Thefe at firil are large intervals of the globular 

 matter, but gradually become fmaller. Membranes are 

 formed round thefe paffages. All parts are firft fluid and 

 inorganic, and then formed into veflels. Trunks are 

 funned to the branches, and at lall the great trunk of all, 

 the heart. New parts are formed, from the juices of the 

 firft.; and thus the organs appear in fucceflion, one after the 

 ether. Haller refutes this theory from his accurate obfer- 

 vations on the formation of the chick ; he fhews that in fadl 

 parts cxill, dilHnguiflied by their form and other charafters, 

 when fuperficial obfervation would lead us to infer that there 

 was only an inorganic homogeneous mafs. The tranfpa- 

 rencyof the whole prevents the outlines and diftinftion from 

 being vifxble, but coagulation by acids brings thefe dirfer- 

 ences into view. Bccaufe the original gelatinous mafs, which 

 forms the animal, feems to have no obvious ilrufture or 

 fmaller diilingulthable component parts, we are not therefore 

 to conclude that it has none. Spirit of wine, poured on this 

 jelly, hardens it fa, that we can fee fibres, vefftls, and vifcera, 

 where tliere fcemod at firfl to be a m.ere tranfparent concrete. 

 There is no effential power in the alcohol to model rude mat- 

 ter into an organic ftrufture ; but the dellrudion of the 

 tranfparency allowed the outlinesof parts to be diflinguifhed: 

 Cmilar explanations may be given of all his obfervations on 

 this fubjeft. Moreover, we can by no means underiland 

 how this fingle power can form fuch different parts always 

 in the fame place in one animal, and according to one arche- 

 type, if the materials be inorganic, mutable, and fufcepti- 

 ble of any configuration. Why ihould this matter aKvays 

 produce, without any error, a chicken in the common fowl, 



a pea-chick in the pea-fowl ? Nothing is aflumed but a di- 

 lating force acfting progrcflivcly ; this might give origin to a 

 vafcular net-work, growing conflanlly larger as lung as the 

 expanfive force exceeded the refinance ; but how docs ii 

 produce a heart, a head, brain, and kidneys? Why is a pe- 

 culiar order of parts formed in each animal ? 



Some again have explained the formation of the body ac- 

 cording to mechanical principles, by the power of fermenta- 

 tion, &c. We caimot, fays Haller, conceive that any power, 

 unlefs guided by intelligence, can aft on matter in a manner 

 conftantly ciianging, and fo direfted, that inorganic materi- 

 als are formed into bones, mufcles, vefll-ls, and vifcera, ar- 

 ranged in a certain order with refpeft to each other. All 

 fpontancous produftions, as for inftance the beautiful figures 

 feen in fnow, are arranged in an unifonn and invariable man- 

 ner. Let any perfon, in order to eftimate the value of fuch 

 hypothefes, refleft merely on the eye. How can this organ 

 be moulded by any expanfive force into fuch various fuccef- 

 five layers, all differently fabricated, where the light pafTcs 

 through tranfparent bodies, every where furrounded by others 

 perfeftly opaque,and fo arranged, that in the milhonsof men 

 and animals the rays of light conftantly converge upon the 

 retina \ Yet this bhnd material caufe knows nothing of light,, 

 nor of the laws by which it is refrafted, although we muit 

 fuppofe it to have adapted all the parts fo accurately, even to 

 the hundredth part of a line, in order to the colleftion of the 

 rays in the retina. Again, this unintelligent caufe has fur- 

 niihed the ej-e with eye-lids and eye -brows, and has given to 

 the iris a power of contraftion and dilatation, by which the 

 organ is accommodated to too great or too fmall a quantity 

 of light. 



liuffon fuppofes the nutritive matter to penetrate all parts 

 of the body, andtobe formed in them, as in an internal moidd ; 

 and he conceives that the fuperfiuous particles are carried 

 back to the femen, conveying into that fluid every thin" 

 neccffary to the produftion of a new being, fimilar to the 

 former. The feminal fluid of either fcx contains the par- 

 ticles necefTary for forming an individual of the fame fex. 



Thefe ir.uft be mixed for the produftion of a new being. 

 The generative organs are the bafis of the new animal, and 

 thefe are firft formed of themfeivcs : the other organic par- 

 ticles of the body are arranged round them as a centre, 

 according to the order, which they held in the body, from 

 which they were produced. Th.at fex prevails, of which the 

 particles are the molt numerous. The author of this hypo- 

 thefis confiders that it explains completely the rcfemblance 

 of the offspring to either or both parents, the formation of • 

 twins, &c. 



The illuftrious name of Buffon can hardly induce us to 

 animadvert ferioully on fuch dreams. In the firfl place, what 

 is an internal mould or model ? The authors of the hypo- 

 thefis are fo far from fatisfying us on this fundamental point, 

 that they confcfs we could not underilandit, unlefs we had 

 a feventh fenfe. How then came they to know it ? So far 

 from underftanding what this model is, we have no heika- 

 tion in afferting that its exiftence is purely ideal. But if 

 we fhould grant this, there are ilill infuperabie difficulties re- 

 maining. Many children arc unlike both parents, and they 

 fometimes have parts which both the tathor and the mother 

 v.'anted, and with which, therefore, neitlur parent cculd 

 have fupplied them ; this is the cafe with the offspring of 

 mutilated individuals, and particularly v,-ith the male chil- 

 dren of fathers who had loft one teftis; a cafe which was not- 

 uncommon when caftration was an ordinary modeof treatino- 

 ruptures. The mother cannot bcftow on her daughter the 

 hymen, Mhich ftie has loft ; nor can we fee the fource from 

 which the foramen otale, the ductus artcricfus, and venofus, . 



the- 



