[239] EXERCITATIO DECIMAQUARTA.
De generatione foetus ex ovo gallinaceo.

14th exercise
The generation of the fetus from the egg of hen

DE ovi gallinacei formatione et generatione, iam dictum est. Sequitur, ut de pulli ex ovo procreatione observationes nostras enarremus. Opus profecto aeque arduum, ac proficuum et iucundum. Latent enim plerumque, veluti in alta nocte, prima naturae stamina; et subtilitate sua, non minus ingenii, quam oculorum aciem eludunt.

Already it has been spoken about the formation and the generation of the egg of hen. It follows that I have to  expound my observations on the birth of the chick from the egg. An enterprise certainly both arduous and useful as well as pleasant. In fact mostly the first threads of the warp of nature keep hidden as in a deep night, and with their thinness they elude the sharpness both of intelligence and eyes.

Neque enim minore fere negotio, intima generationis arcana, et obscura principia, quam mundi totius compagem, et creationis modum inveneris. Durat, reciproco hoc generationis et corruptionis ordine, rerum aeternitas: Et quemadmodum sol oriens occidensque perpetuis suis circumgyrationibus aevum complet: ita similiter caducae res mortalium alternis individuorum vicissitudinibus, redintegrata semper eadem specie, perennant.

In fact with almost identical difficulty you will discover the intimate secrets and the dark principles of the generation as well as the structure of the whole world and the manner of the creation. Because this mutual succession of creation and corruption, the eternity of the things continues to exist. And as the sun rising and setting with its continuous twirls ends one year, so in a similar way the transient things of the mortals with the alternate vicissitudes of the individuals keep perennial the renewed things always in the same way.

Auctores, qui hac de re quidquam tractarunt, fere omnes diversum iter ingressi sunt: quod nempe privatis opinionibus, pridem receptis, occupata mens ad consimilia exstruenda dogmata inclinaret.

The authors who attended a little bit to this matter, almost all turned into a different path: just because the mind, occupied by particular opinions gathered since a long time, was making to be inclined to realize analogous affirmations.

[240] Aristoteles[1] olim, nuperque Hieronymus Fabricius, de generatione et formatione pulli ex ovo, accurate adeo scripserunt, ut pauca admodum desiderari videantur. Ulysses Aldrovandus[2] tamen ovi pullulationem ex suis observationibus descripserit; qua in re, ad Aristotelis auctoritatem potius, quam experientiam ipsam collimasse videtur. Quippe eodem tempore Volcherus Coiter Bononiae degens, eiusdem Ulyssis, praeceptoris sui, ut ait, hortatu, quotidie ova incubata aperuit, plurimaque vere elucidavit, secus quam Aldrovando[3] factum est; quae tamen hunc latere non poterant. Aemilius Parisanus quoque, medicus Venetus, explosis aliorum opinionibus, novam pulli ex ovo procreationem commentus est.

Once Aristotle, and recently Girolamo Fabrizi, wrote in a so accurate manner about the generation and the formation of the chick from the egg, that very few things would be regarded as necessary. Nevertheless Ulisse Aldrovandi* would have described the generation of the chick from the egg according to his own observations; it seems that on this point he turned the glance to the authority of Aristotle rather than to a true experience. Really in the same period Volcher Coiter*, who was dwelling in Bologna, on incitement of Ulisse himself, his own teacher, as he affirms, opened every day incubated eggs and truly he clarified a lot of things, otherwise Aldrovandi did, all things that to the latter would not be remained unknown. Also Emilio Parisano*, physician in Venice, after having disapproved of the ideas of others, invented a new generation of the chick from the egg.

Quoniam tamen, secundum ea quae a nobis observata sunt, nonnulla magni momenti aliter longe se habent atque alii hactenus tradiderunt; quid quotidie in ovo agatur, et quae partes transmutentur, referam: praesertim primis incubationis diebus; quo tempore maxime omnia obscura, confusa, observatuque ardua sunt; et auctores potissimum pro suis observationibus digladiantur; quas nempe praeconceptis suis opinionibus (de causis generationis animalium materiali et efficiente) magis, quam veritati ipsi accommodant.

Nevertheless, since according to those things I observed, some have a great importance in comparison to what others related till now, I will report what daily happens in the egg and what parts are transforming, above all in the first days of incubation, a period in which all the things are very obscure, confused and difficult to be observed, and the authors doggedly contend for they are their observations, that really they attribute more to their preconceived points of view (on material and efficient causes of the generation of animals) rather than to the truth.

Quae Aristoteles de procreatione pulli narrat, verissima sunt. Nihilominus, quasi ipsemet ea non vidisset, sed ab experto quodam accepisset, temporibus quaeque suis haud recte distinguit: plurimumque fallitur circa locum, in quo primum ovi principium sit, quem in acuta eius parte statuit; eoque nomine a Fabricio merito reprehenditur. Nec videtur principium pulli in ovo observasse; aut ibidem reperire potuisse ea, quae in omni generatione dixerat necessaria. Materiam nimirum constitutivam (cum ex nihilo quidquam naturaliter fieri, impossibile sit) albumen esse voluit. Et quomodo efficiens causa (galli semen [241] nempe) citra tactu agat; aut ovum ipsum sponte sua, sine ulla inhaerente maris genitura, foetum efficiat haud satis intellexit.

The things narrated by Aristotle about the procreation of the chick are extremely true. Nevertheless, as if he didn't see them personally, but he received them from an expert, he distinguishes in an very incorrect way every thing according to their chronology, and he is wrong above all about the point where the initial principle of the egg is located, that he established to be in its acute part, and for such reason he is rightly criticized by Fabrizi. Neither it seems that he observed in the egg the principle of the chick, nor that he has been able to find those things he told to be necessary in every generation. He established that the albumen is without doubt the constituent matter (being impossible that something is naturally formed from nothing). And he didn't understand in a sufficient way how the efficient cause (that is, the semen of the cock) acts besides through the direct contact, or that the egg itself spontaneously, without joining with any sperm of the male, is able to create a fetus.

Aldrovandus eiusdem erroris cum Aristotele affinis, ait praeterea, quod nulli oculi, nisi caeci, concesserint vitellum primis statim diebus ad acutum ovi angulum assurgere: putatque grandines esse semen galli, atque ab ipsis pullum constitui; nutriri autem tum a vitello, tum ab albumine. Plane contra Aristotelis sententiam, qui grandines nihil ad ovi foecunditatem facere arbitratur.

Aldrovandi, accomplice with Aristotle of the same error, says besides that no eye, unless being blind, would admit that «immediately in the first days the yolk rises toward the acute angle of the egg», and he believes that the chalazae are the semen of the cock and that by them the chick is constituted, while it is fed both by yolk and albumen. Clearly against the affirmation of Aristotle, who believes that the chalazae don't work at all to the fertility of the egg.

Veriora multo, et autopsiae magis consona Volcherus Coiter[4]. De tribus tamen globulis quae narrat, fabulae sunt. Nec principium, unde foetus in ovo oriatur, recte perspexit.

Volcher Coiter reports more truthful things and more in accordance with what it is seen by our own eyes. Nevertheless what he tells about the three globules is a fib. Neither he recognized in a corrected way the principle whence the fetus is born in the egg.

Hieronymus Fabricius quidem contendit, grandines non esse galli semen; ex ipsis tamen galli semine foecundatis pullum, tanquam ex materia, corporari voluit. Vidit etiam principium pulli in ovo; maculam nempe, sive cicatriculam vitelli tunicae adnatam: sed eam duntaxat pedunculi abrupti vestigium esse, et ovi affectionem quandam, non autem partem principalem, iudicavit.

Actually Girolamo Fabrizi affirms that «the chalazae are not the semen of the cock, nevertheless from them, fertilized by the semen of the cock, he wanted that the chick is taking life as if being the first matter.» He also saw the principle of the chick in the egg, that is, a spot or cicatricle, sprouted on the tunic of the yolk. But he believed that it is only a residue of the broken peduncle and a secondary part of the egg, not the principal part.

Parisanus sententiam Fabricii de chalazis abunde refutavit; ipsemet tamen in circulis quibusdam, et partium principalium foetus (iecoris nempe et cordis) punctis, manifeste hallucinatur. Videtur etiam observasse principium foetus: sed, quid esset, ignorasse; cum ait, punctum album, in circulorum medio, galli semen esse, ex quo fit pullus.

Emilio Parisano abundantly contested the opinion of Fabrizi about the chalazae. Nevertheless he raves in a patent way about some circular formations and about some points of the principal parts of the fetus (that is, of liver and heart). He also seems to have observed the principle of the fetus, but that ignored what it was, since he says «a white point at the center of the circles, it is the semen of the cock, from which the chick is formed.»

Ita contigit, ut singuli, dum ad praeconceptas dudum opiniones formationis pulli in ovo rationes exigunt, a vero scopo aberrarent. Alii nimirum sanguinem aut semen materiam esse censent, unde pullus constituatur: aliis semen videtur opifex, seu causa efficiens, quae eundem fabricet. Cum tamen accuratius rem omnem perpendenti certum sit, nullam ibidem paratam [242] esse materiam; nec sanguinem menstruum adesse, quem semen maris coitus tempore coagulet, ut voluit Aristoteles; nec pullum ex semine maris, aut foeminae, aut utrisque commistis, in ovo oriundum esse.

So it happened that every one, when wanting to agree with the just since long time preconceived opinions about the formation of the chick in the egg, he strayed from the true target. Some people are just believing that the blood or the semen are the first matter from which the chick is constituted, to others the semen seems to be the maker or the efficient cause creating it. Nevertheless, for he who examines every thing with a certain accuracy comes out certain that there is not prepared any first matter, neither that there is the menstrual blood which the semen of the male coagulates in the period of joining, as Aristotle stated, nor that the chick has to be born in the egg from the semen of male or female or from both mixed.