Chapter XXXIV: Introduction (9)

In the former of the ways mentioned, the generation of insects is effected where by metamorphosis a worm is born from an egg; or out of a putrescent material, the drying of a moist substance or the moistening of a dry one, rudiments are created, from which, as from a caterpillar grown to its full size, or from an aurelia, springs a butterfly or fly already of a proper size, which never attains to any larger growth after it is first born; this is called metamorphosis. But the more perfect animals with red blood are made by epigenesis, or the superaddition of parts. In the former, chance or hazard seems the principal promoter of generation, and there, the form is due to the potency of a preexisting material; and the first cause of generation is ‘matter,’ rather than ‘an external efficient;’ whence it happens too that these animals are less perfect, less preservative of their own races, and less abiding, than the red-blooded terrestrial or aquatic animals, which owe their immortality to one constant source, viz. the perpetuation of the same species; of this circumstance we assign the first cause to nature and the vegetative faculty.

Some animals then are born of their own accord, concocted out of matter spontaneously, or by chance, as Aristotle seems to assert, when he speaks of animals whose matter is capable of receiving an impulse from itself, viz. the same impulse given by hazard, as is attributable to the seed, in the generation of other animals. And the same thing happens in art, as in the generation of animals. Some things, which are the result of art, are so likewise of chance, as good health; others always owe their existence to art; for instance, a house. Bees, wasps, butterflies, and whatever is generated from caterpillars by metamorphosis, are said to have sprung from chance, and therefore to be not preservative of their own race; the contrary is the case with the lion and the cock; they owe their existence as it were to nature or an operative faculty of a divine quality, and require for their propagation an identity of species, rather than any supply of fitting material.

In the generation by metamorphosis forms are created as if by the impression of a seal, or, as if they were adjusted in a mould; in truth the whole material is transformed. But an animal which is created by epigenesis attracts, prepares, elaborates, and makes use of the material, all at the same time; the processes of formation and growth are simultaneous. In the former the plastic force cuts up, and distributes, and reduces into limbs the same homogeneous material; and makes out of a homogeneous material organs which are dissimilar. But in the latter, while it creates in succession parts which are differently and variously distributed, it requires and makes a material which is also various in its nature, and variously distributed, and such as is now adapted to the formation of one part, now of another; on which account we believe the perfect hen’s-egg to be constituted of various parts.

Now it appears clear from my history, that the generation of the chick from the egg is the result of epigenesis, rather than of metamorphosis, and that all its parts are not fashioned simultaneously, but emerge in their due succession and order; it appears, too, that its form proceeds simultaneously with its growth, and its growth with its form; also that the generation of some parts supervenes on others previously existing, from which they become distinct; lastly, that its origin, growth, and consummation are brought about by the method of nutrition; and that at length the fœtus is thus produced. For the formative faculty of the chick rather acquires and prepares its own material for itself than only finds it when prepared, and the chick seems to be formed and to receive its growth from no other than itself. And, as all things receive their growth from the same power by which they are created, so likewise should we believe, that by the same power by which the chick is preserved, and caused to grow from the commencement, (whether that may have been the soul or a faculty of the soul,) by that power, I say, is it also created. For the same efficient and conservative faculty is found in the egg as in the chick; and of the same material of which it constitutes the first particle of the chick, out of the very same does it nourish, increase, and superadd all the other parts. Lastly, in generation by metamorphosis the whole is distributed and separated _into_ parts; but in that by epigenesis the whole is put together _out of_ parts in a certain order, and constituted _from_ them.

Wherefore Fabricius was in error when he looked for the material of the chick, (as a distinct part of the egg, from which its body was formed,) as if the chick were created by metamorphosis, or a transformation of the material in mass; and as if all, or at least the principal parts of the body sprang from the same material, and, to use his own words, were incorporated simultaneously. [He is, therefore, of course opposed to the notion] of the chick being formed by epigenesis, in which a certain order is observed according to the dignity and the use of parts, where at first a small foundation is, as it were, laid, which, in the course of growth, has at one and the same time distinct structures formed and its figure established, and acquires an additional birth of parts afterwards, each in its own order; in the same way, for instance, as the bud bursting from the top of the acorn, in the course of its growth, has its parts separately taking the form of root, wood, pith, bark, boughs, branches, leaves, flowers, and fruit, until at length out comes a perfect tree; just so is it with the creation of the chick in the egg: the little cicatrix, or small spot, the foundation of the future structure, grows into the eye and is at the same time separated into the colliquament; in the centre of which the punctum sanguineum pulsans commences its being, together with the ramification of the veins; to these is presently added the nebula, and the first concretion of the future body; this also, in proportion as its bulk increases, is gradually divided and distinguished into parts, which however do not all emerge at the same time, but one after the other, and each in its proper order. To conclude, then: in the generation of those animals which are created by epigenesis, and are formed in parts, (as the chick in the egg,) we need not seek one material for the incorporation of the fœtus, another for its commencing nutrition and growth; for it receives such nutrition and growth from the same material out of which it is made; and, vice versâ, the chick in the egg is constituted out of the materials of its nutrition and growth. And an animal which is capable of nutrition is of the same potency as one which is augmentative, as we shall afterwards show; and they differ only, as Aristotle says, in their distinctness of being; in all other respects they are alike. For, in so far as anything is convertible into a substance, it is nutritious, and under certain conditions it is augmentative: in virtue of its repairing a loss of substance, it is called nutriment, in virtue of its being added, where there is no such loss of substance, it is called increment. Now the material of the chick, in the processes of generation, nutrition, and augmentation is equally to be considered as aliment and increment. We say simply that anything is generated, when no part of it has pre-existed; we speak of its being nourished and growing when it has already existed. The part of the fœtus which is first formed is said to be begotten or born; all substitutions or additions are called adnascent, or aggenerate. In all there is the same transmutation or generation from the same to the same; as concerns a part, this is performed by the process of nutrition and augmentation, but as regards the whole, by simple generation; in other respects the same processes occur equally. For from the same source from which the material first takes its existence, from that source also does it gain nutriment and increase. Moreover, from what we shall presently say, it will be made clear that all the parts of the body are nourished by a common nutritious juice; for, as all plants arise from one and the same common nutriment, (whether it be dew or a moisture from the earth,) altered and concocted in a diversity of manners, by which they are also nourished and grow; so likewise to identical fluids of the egg, namely, the albumen and the yelk, do the whole chick and each of its parts owe their birth and growth.

We will explain, also, what are the animals whose generation takes place by metamorphosis, and of what kind is the pre-existent material of insects which take their origin from a worm or a caterpillar; a material from which, by transmutation alone, all their parts are simultaneously constituted and embodied, and a perfect animal is born; likewise, to what animals any constant order in the successive generation of their parts attaches, as is the case with such as are at first born in an imperfect condition, and afterwards grow to maturity and perfection; and this happens to all those that are born from an egg. As in these the processes of growth and formation are carried on at the same time, and a separation and distinction of parts takes place in a regularly observed order, so in their case is there no immediate pre-existing material present, for the incorporation of the fœtus, (such as the mixture of the semina of the male and female is generally thought to be, or the menstrual blood, or some very small portion of the egg,) but as soon as ever the material is created and prepared, so soon are growth and form commenced; the nutriment is immediately accompanied by the presence of that which it has to feed. And this kind of generation is the result of epigenesis as the man proceeds from the boy; the edifice of the body, to wit, is raised on the punctum saliens as a foundation; as a ship is made from a keel, and as a potter makes a vessel, as the carpenter forms a footstool out of a piece of wood, or a statuary his statue from a block of marble. For out of the same material from which the first part of the chick or its smallest particle springs, from the very same is the whole chick born; whence the first little drop of blood, thence also proceeds its whole mass by means of generation in the egg; nor is there any difference between the elements which constitute and form the limbs or organs of the body, and those out of which all their similar parts, to wit, the skin, the flesh, veins, membranes, nerves, cartilages, and bones, derive their origin. For the part which was at first soft and fleshy, afterwards, in the course of its growth, and without any change in the matter of nutrition, becomes a nerve, a ligament, a tendon; what was a simple membrane becomes an investing tunic; what had been cartilage is afterwards found to be a spinous process of bone, all variously diversified out of the same similar material. For a similar organic body (which the vulgar believe to consist of the elements) is not created out of elements at first existing separately, and then put together, united, and altered; nor is it put together out of constituent parts; but, from a transmutation of it when in a mixed state, another compound is created: to take an instance, from the colliquament the blood is formed, from the blood the structure of the body arises, which appears to be homogeneous in the beginning, and resembles the spermatic jelly; but from this the parts are at first delineated by an obscure division, and afterwards become separate and distinct organs.

Those parts, I say, are not made similar by any successive union of dissimilar and heterogeneous elements, but spring out of a similar material through the process of generation, have their different elements assigned to them by the same process, and are made dissimilar. Just as if the whole chick was created by a command to this effect, of the Divine Architect: “let there be a similar colourless mass, and let it be divided into parts and made to increase, and in the meantime, while it is growing, let there be a separation and delineation of parts; and let this part be harder, and denser, and more glistening, that be softer and more coloured,” and it was so. Now it is in this very manner that the structure of the chick in the egg goes on day by day; all its parts are formed, nourished, and augmented out of the same material. First, from the spine arise the sides, and the bones are distinguishable from the flesh by minute lines of extreme whiteness; in the head three bullæ are perceived, full of crystalline fluid, which correspond to the brain, the cerebellum, and one eye, easily observable by a black speck; the substance which at first appears a milky coagulum, afterwards gradually becomes cartilaginous, has spinous processes attached to it, and ends in being completely osseous; what was at first of a mucous nature and colourless, is converted at length into red flesh and parenchyma; what was at one time limpid and perfectly pure water, presently assumes the form of brain, cerebellum, and eyes. For there is a greater and more divine mystery in the generation of animals, than the simple collecting together, alteration, and composition of a whole out of parts would seem to imply; inasmuch as here the whole has a separate constitution and existence before its parts, the mixture before the elements. But of this more at another time, when we come to specify the causes of these things.

EXERCISE THE FORTY-SIXTH.

_Of the efficient cause of the generation of the chick and fœtus._

We have thus far spoken of the matter from which the chick in ovo is generated. We have still with Fabricius to say a few words on the efficient cause of the chick. As this subject is surrounded with difficulties, however; as writers nowhere else dispute more virulently or more wordily, and Aristotle himself in explaining the matter is singularly intricate and perplexed, and as various questions that can by no means be lightly treated do in fact present themselves for consideration, I conceive that I shall be undertaking a task worthy of the toil if, as I have done in the disquisition on the “matter,” I set out here by stating in how many ways anything can be said to be “efficient” or “effective.” We shall thus obtain a clearer idea of what it is which we are to inquire after under the name of “efficient,” and further, what estimate we are to form of the ideas of writers upon this subject; it will at the same time appear from our observations what is truly and properly to be called “an efficient.”

Aristotle[253] defines an efficient cause to be that “whence is derived the first principle of change or quiescence; as a counsel, a father; and simply as doing that which is done; the transmute of the thing transmuted.” In the generation of animals accordingly many and various kinds of cause inducing motion are brought forward; sometimes an accident or quality is assigned; and so animal heat and the formative faculty are called efficient causes. Sometimes it is an external substance, previously existing, in which inheres the plastic force or formative faculty that is designated in the same way; as the cock or his seminal fluid, by the influence of which the chick is procreated from the egg. Occasionally it is some internal substance, self-existent, such as spirit, or innate heat. And again, it is some other substance, such as form, or nature, or soul, or some portion of the vegetative soul, that is regarded as the efficient, such a principle as we have already declared to inhere in the egg.

Besides, since one thing whence motion proceeds is nearer and another more remote, it sometimes happens that the media between the prime efficient and the thing last effected, and instruments are regarded as efficient causes; subordinate conclusions, likewise, or the principles of subsequents, are reckoned among the number of efficient causes; in this way some parts are themselves spoken of as genital parts, such as the heart, whence Aristotle affirms that all the rest of the body is produced; a statement which we have found borne out by our history. The heart, I repeat, or at all events its rudimentary parts, namely, the vesicle and pulsating point, construct the rest of the body as their future dwelling-place; when erected it enters and conceals itself within its habitation, which it vivifies and governs, and applying the ribs and sternum as a defence, it walls itself about. And there it abides, the household divinity, first seat of the soul, prime receptacle of the innate heat, perennial centre of animal action; source and origin of all the faculties; only solace in adversity!

Moreover, since the “efficient” is so styled with reference to the effect, as some parts produced by epigenesis are posterior 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, different motions likewise proceed. Thus physicians in their physiologies assign certain organs as the agents of chylification, others of sanguification, others of generation, &c.; and anatomists 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 differing 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 necessary, seeing, that unless they are associated or intervene, nothing 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 incubation, 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 reckoned 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 accidentals, 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; keeping 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 fœtus, 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 we inquire what is the “efficient,” the architect, the adviser, but that we likewise venerate and adore the omnipotent Creator and preserver of a work, which has been well entitled a microcosm. We also ask whence this divine something comes, when it arrives, and where it resides in the egg; this something which is analogous to the essence of the stars, and is near akin to art and intelligence, and the vicar of the Almighty Creator?

From what precedes it will be apparent how difficult it were to enumerate all the efficient causes of the chick; it is indispensable, indeed, in the complete investigation of this subject to refer to a general disquisition; we could not from the single generation of the chick in ovo, and without clearer light derived from investigations extended to other animals, venture on conclusions that should be applicable to the whole animal creation. And this all the more, since Aristotle himself has enumerated such a variety of efficient principles of animals; for he at one time adduces the ‘male’[254] as the principal efficient cause, as that, to wit, in which the reason of the engendered chick resides, according to the axiom;[255] “all things are made by the same ‘univocal:’” at another time he takes ‘the male semen;’[256] or, ‘the nature of the male emitting semen:’[257] sometimes it is ‘that which inheres in the semen,’[258] ‘which causes seeds to be prolific, spirit, to wit, and nature in that spirit corresponding in its qualities to the essence of the stars:’ elsewhere he says it is ‘heat;’[259] ‘moderate heat;’[260] ‘a certain and proportionate degree of heat;’[261] ‘the heat in the blood;’[262] ‘the heat of the ambient air;’ ‘the winds;’[263] ‘the sun;’ ‘the heavens;’ ‘Jupiter;’ ‘the soul;’ and, somewhere, nature is spoken of by him as ‘the principle of motion and rest.’

Aristotle[264] concludes the discussion on the efficient cause by declaring it “extremely doubtful” whether it be “anything extrinsic; or something inherent in the geniture or semen; and whether it be any part of the soul, or the soul itself, or something having a soul?”

To escape from such a labyrinth of “efficient causes,” it were necessary to be furnished with Ariadne’s thread, composed from observations on almost every animal that lives; on this account the subject is deferred till we come to our more general disquisition. Meantime we shall recount the particulars which either manifestly appear in the special history of the chick from the egg, or which differ from the ideas usually entertained, or that seem to demand further inquiry.

EXERCISE THE FORTY-SEVENTH.

_Of the manner in which the efficient cause of the chick acts, according to Aristotle._

It is universally allowed, that the male is the primary efficient cause in generation, on the ground that in him the species or form resides; and it is further affirmed, that the emission of his ‘geniture’ during coition, is the cause both of the existence and the fertility of the egg. But none of the philosophers nor physicians, ancient or modern, have sufficiently explained in what manner the seed of the cock produced a chick from the egg; nor have they solved the question proposed by Aristotle. Nor, indeed, is Aristotle himself much more explanatory, when he says, “that the male contributes not in respect of quantity, but of quality, and is the origin of action; but that it is the female which brings the material.” And a little after, “It is not every male that emits seed, and in those which do so, this is no part of the fœtus; just as in the case of a carpenter, nothing is translated from him to the substance of the wood which he uses, nor does any part of the artist’s skill reside in the work when completed; but a form and appearance are given by his operation to the matter; and the soul, which originates the idea of forms, and the skill to imitate them, moves the hands, or other limb, whatever it may be, by a motion of a certain quality; or from diversity proceeds difference; or from similarity proceeds resemblance. But the hands and instruments move the material. So the nature of a male, which emits semen, uses that semen as an instrument, and an act having motion; as in works of art the instruments are moved, for in them, in some sort, the motion of the art exists.”

By these words he seems to imply, that generation is owing to the motion of a certain quality. Just as in art, though the first cause (the “ratio operis”) be in the mind of the artist, yet afterwards, the work is effected by the movement of the hands or other instruments; and although the first cause be removed (as in automatons,) yet is it in some sort said to move what it now does not touch, but once has touched, so long as motion continues in the instrument.

Also in the next book, he says: “When the semen of the male has arrived as far as the uterus of the female, it arranges and coagulates the purest part of the excrement (meaning the menstrual blood existing in the uterus); and, by a motion of this kind, changes the material, which has been prepared in the uterus, till it forms part of the chick; and this, hereafter, although the semen after the performance of this motion disappears, exists as part of the fœtus, and becomes animate (as the heart,) and regulates its own powers and growth, as a son emancipated from his father, and having his own establishment. And so it is necessary that there be some commencing principle, from which afterwards the order of the limbs may be delineated, and a proper disposition made of those things that concern the absolution of the animal; a principle, which may be the source of growth and motion to all the other parts; the origin of all, both similar and dissimilar parts, and the source of their ultimate aliment. For that which is already an animal grows, but the ultimate aliment of an animal is the blood, or something corresponding to the blood, whose vessels and receptacles are the veins; wherefore, the heart is the origin of the veins. But veins, like roots, spread to the uterus, and through these the fœtus derives its nourishment. The heart too, being the beginning of all nature and the containing end, ought to be made first; as if it were a genital part by its own nature, which, as the original of all the other parts, and of the whole animal, and of sense, must needs be the first; and by its heat, (since all the parts are in the material _potentially_,) when once the beginning of the motion has taken place, all that follows is excited, just as in spontaneous miracles; and the parts are commenced, not by change of place, but by alteration in softness, hardness, temperature, and the other differences observed in similar parts, these being now actually made, which had before existed only potentially.”

This is, in nearly so many words, the opinion of Aristotle, which supposes that the fœtus is formed from the seed by motion, although it is not at present in communication with the fœtus, but simply has been so at a former time: his reasonings are, indeed, ingenious, and carefully put together, and from what we see in the order of the generation of parts, not improbable. For the heart, with the channel of the veins, is first noticed as an animate principle, in which motion and sense reside; or, as it were, an emancipated son, and a genital part, whence the order of the members is delineated, whence all things pertaining to the completion of the animal are disposed, and which has all the attributes bestowed upon it by Aristotle.

But it seems impossible, that the heart should be formed in the egg by the seed of the male, when that seed neither exists in the egg, nor touches it, nor ever has touched it; because the seed does not enter the uterus where the egg is, (as is allowed by Fabricius,) nor is in any way attracted by it; nay, even the maternal blood is not in the egg, nor any other prepared matter, out of which the seed of the male may form this genital part, the author of all the others. For it is not immediately after coition, while the seed still remains within the body, and is in communication, that any part of the chick exists in the egg, but after many days, when incubation has taken place. Moreover, in fishes, when the geniture of the male does nothing but touch the eggs externally, and does not enter into them, it is not likely that it performs any more ample functions when the agency is external, than does the seed of the cock in the already formed eggs of the hen. Besides, since immediately after coition no trace of the egg as yet exists, but it is afterwards generated by the hen herself (I am speaking of the prolific egg); when now the seed of the cock is departed and vanished, there is no probability that the fœtus is formed in that egg by the aforesaid seed, through means of one or any number of successive motions.

Nor indeed does the difference between prolific and unprolific or wind eggs consist herein, that the former contained the seed of the male, as Aldrovandus supposed; nor has it been noticed that anything has been formed and coagulated in the egg by the seed of the male, nor has any sensible transmutation been discovered (for indeed, there is no sensible difference between the fertile and the wind egg); and yet a prolific egg, conceived long after coition, has in itself the faculties of both sexes; viz., the capability of being both formed itself, and of forming a chick; as if, according to the idea of Aristotle, it had derived its origin from the coition of the two, and their mutual endeavours towards the same end; and compelled by the force of this argument, as mentioned above, when speaking of the generation of the ovum, he has endowed the egg with a vital principle (anima.) If such really exist, then, without doubt it would be the origin and efficient of all the natural phenomena which take place in the egg. For if we consider the structure of the chick, displaying, as it does, so much art, so divine an intelligence and foresight; when we see the eyes adapted for vision, the bill for taking food, the feet for walking, the wings for flying, and similarly the rest of its parts, each to its own end, we must conclude, whatever the power be which creates such an animal out of an egg, that it is either the soul, or part of the soul, or something having a soul, or something existing previous to, and more excellent than the soul, operating with intelligence and foresight.

From the generation of the chick, it is also manifest that, whatever may have been its principle of life or first vegetative cause, this cause itself first existed in the heart. Now, if this be the soul of the chicken, it is equally clear, that that soul must have existed in the punctum saliens and the blood; since we there discover motion and sense; for the heart moves and leaps like an animal. But if a soul exists in the punctum saliens, forming, nourishing, and augmenting the rest of the body, in the manner which we have pointed out in our history, then it, without doubt, flows from the heart, as from a fountain-head, into the whole body. Likewise, if the existence of the vital principle (anima) in the egg, or, as Aristotle supposes, if the vegetative part of the soul be the cause of its fertility, it must follow that the punctum saliens, or animate genital part, proceeds from the vital principle (anima) of the egg, (for nothing is its own author,) and that the said vital principle (anima) passes from the egg into the punctum saliens, presently into the heart, and thence into the chick.

Moreover, if the egg have a prolific virtue, and a vegetative soul, by which the chick is constructed, and if it owe them, as is allowed on all hands, to the semen of the cock; it is clear that this semen is also endowed with an active principle (anima.) For such is Aristotle’s opinion, when he expresses himself as follows: “As to whether the semen has a vital principle (anima) or not, the same reasoning must be adduced which we have employed in the consideration of other parts. For no active principle (anima) can exist, except in that thing whose vital principle it is; nor can there be any part which is not partaker of the vital principle, except it be equivocally, as the eye of a dead man. We must, therefore, allow, both that the semen has an active principle (anima) and is potential.”

Now from these premises, it follows that the male is the primary efficient in which the ratio and forma reside, which produces a seed or rather a prolific geniture, and imparts it, imbued as it is with an anima vegetativa (with which also the rest of its parts are endowed) to the female. The introduction of this geniture begets such a movement in the material of the hen, that the production of an animate egg is the result, and from thence too the first particle of the chick is animated, and afterwards the whole chick. And so, according to Aristotle, either the same soul passes, by means of some metempsychosis, from the cock into his geniture, from the geniture into the material of the female, thence into the egg, and from the egg into the chick; or else, it is raised up in each of the subsequent things by its respective antecedent; namely, in the seed of the male by the male himself, in the egg by the seed, last in the chick by the egg, as light is derived from light.

The efficient, therefore, which we look for in the egg, to explain the birth of the chick, is the vital principle (anima); and therefore, the vital principle of the egg; for, according to Aristotle, a soul does not exist except in that thing whose soul it is.

But it is manifest, that the seed of the male is not the efficient of the chick; neither as an instrument capable of forming the chick by its motion, as Aristotle would have it, nor as an animate substance transferring its vitality (anima) to the chick. For in the egg there is no semen, neither does any touch it, nor has ever done so; (“and it is impossible that that which does not touch should move, or that anything should be affected by that which does not move it,”) and therefore the vitality of the semen ought not to be said to exist in it; and although the vital principle may be the efficient in the egg, yet it would not appear to result more from the cock or his semen, than from the hen.

Nor, indeed, is it transferred by any metempsychosis or translation from the cock and his semen into the egg, and thence into the chick. For how can this translation be carried on into the eggs that are yet to exist, and to be conceived after intercourse? unless either some animate semen be in the mean time working in some part of the hen; or the vital principle only have been translated without the seed, in order to be infused into any egg which might thereafter be produced; but neither of these alternatives is true. For in no part of the hen is the semen to be found; nor is it possible that the hen after coition should be possessed of a double vital principle, to wit, her own, and that of the future eggs and chicks; since “the living principle or soul is said to be nowhere but in that thing whose soul it is,” much less can one or more vital principles lie hidden in the hen, to be afterwards subservient to the future eggs and chicks in their order, as they are produced.

We have adduced these passages out of Aristotle in order to set forth his opinion of the manner in which the seed of the cock produces the chick from the egg; and thereby throw at least some light on this difficult question. But whereas the said passages do not explain the mode in which this is accomplished, nor even solve the doubts proposed by himself, it appears that we are still sticking in the same mud, and caught in the same perplexities (concerning the efficient cause of the fœtus in the generation of animals;) indeed, so far from Aristotle’s arguments rendering this question more clear, they appear on the contrary to involve it in more and greater doubts.

Wherefore it is no wonder that the most excellent philosopher was in perplexity on this head, and that he has admitted so great a variety of efficient causes, and at one time has been compelled to resort to automatons, coagulation, art, instruments, and motions, for illustrations; at another time to an ‘anima’ in the egg, and in the seed of the male. Moreover, when he seems positively and definitively to determine what it is in each seed, whether of plants or animals, which render the same fertile, he repudiates heat and fire as improper agents; nor does he admit any faculty of a similar quality; nor can he find anything in the seed which should be fit for that office; but he is driven to acknowledge something incorporeal, and coming from foreign sources, which he supposes (like art, or the mind) to form the fœtus with intelligence and foresight, and to institute and ordain all its parts for its welfare. He takes refuge, I say, in a thing which is obscure and not recognizable by us; namely, in a spirit contained in the seed, and in a frothy body, and in the nature in that spirit, corresponding in proportion to the elements of the stars. But what that is, he has nowhere informed us.

EXERCISE THE FORTY-EIGHTH.

_The opinion of Fabricius on the efficient cause of the chick is refuted._

As I have chosen Aristotle, the most eminent among the ancient philosophers, and Fabricius of Aquapendente, one of the foremost anatomists of modern times, as my especial guides and sources of information on the subject of animal generation, when I find that I can make nothing of Aristotle upon a particular topic, I straightway turn to Fabricius; and now I desire to know what he thought of the efficient cause of generation.

I find that he endeavours to satisfy three doubts or difficulties involved in this subject: First, What is the ‘efficient’ of the chick? This he answers, by saying, the semen of the male. Secondly, How does this appear in the egg, and in what way does the semen of the cock fecundate the egg? Thirdly and lastly, In what order are the parts of the chick engendered?

As to the first query, it appears from our observations, that the cock and his seminal fluid are verily the ‘efficient,’ but not the ‘adequate’ cause of generation; that the hen comes in here as something. In this place, therefore, we are principally to inquire how the semen of the cock fecundates the egg otherwise unprolific, and secures the engenderment of a chick from it?

But let us hear Fabricius:[265] “Those things differ,” he observes, “that are produced from eggs, from those that originate from semen, in this, that oviparous animals have the matter from which the embryo is incorporated distinct and separate from the agent; whilst viviparous animals have the efficient cause and the matter associate and concorporate. For the ‘agent’ in the oviparous animal is the semen of the male, in the fowl the semen of the cock, which neither is nor can be in the egg; the ‘matter,’ again, is the chalazæ from which the fœtus is incorporated. These two differ widely from one another; for the chalazæ are added after the vitellus is formed, whilst it is passing through the second uterus, and are an accession to the internal egg; the semen galli, on the contrary, is stored near the fundament, is separated from the chalazæ by a great interval, and nevertheless by its irradiating faculty, fecundates both the whole egg and the uterus. Now in the viviparous animal, the semen is both ‘matter’ and ‘agent,’ the two consisting and being conjoined in the same body.”

Our author appears to have introduced this distinction between oviparous and viviparous animals, that he might spare, or at all events, that he might not directly shock or upset the notions of medical writers on the generation of man, they teaching that the seminal fluids of either sex, projected together in intercourse, are mingled; that as one or other preponderates, this becomes the ‘efficient,’ that stands in lieu of the ‘matter;’ and that the two together, tending to the same end, amalgamate into the ‘conception’ of the viviparous animal.

But when he finds that neither in the egg nor uterus of the fowl is there any semen or blood, and avows his belief that nothing is emitted by the male in intercourse, that can by possibility reach the uterus of the female, nor in the egg discovers a trace of aught supplied by the male, he is compelled to doubt how the semen, which is nowhere to be detected, which is neither mixed with the ‘geniture’ of the female, nor yet is added to it, nor touches it, can fecundate the egg, or constitute the chick. And this all the more urgently, when he has stated that a few connections in the beginning of the season suffice to secure the fecundity of all the eggs that will be laid in its course. For how should it seem otherwise than impossible that from the semen galli communicated in the spring, but now long vanished, lost or consumed, the eggs that continue to be laid through the summer and autumn, should still be rendered fruitful and fit to produce pullets?

It is that he may meet such a difficulty half way, that he coins the difference which has been noticed. By way of bolstering up his views, he farther adduces three additional considerations:--First, since the semen galli is neither extant in the egg, nor was ever present in the uterus, nor is added as ‘material cause’ as in viviparous animals, he has chosen to make it resident for a whole year in the body of the hen. And then that he may have a fit receptacle or storehouse for the fecundating fluid, he finds a blind sac near the inlet to the uterus, in which he says the cock deposits his semen, wherein, as in a treasury, it is stored, and from which all the eggs are fecundated. Lastly, although the semen in that bursa comes into contact neither with the uterus, nor the egg, nor the ovary, whereby it might fecundate the egg, or secure the generation of a chick, he says, nevertheless, that from thence, a certain spiritual substance or irradiation penetrates to the egg, fecundates its chalazæ, and from these produces a chick. By this affirmation, however, he appears to support the opinion of Aristotle, namely, that the female supplies the ‘matter’ in generation, the male the ‘efficient force;’ and to oppose the postulate of medical writers about the mixture of seminal fluids, for the sake of which, nevertheless, as I have said, he seems to have laid down his distinction between oviparous and viviparous animals. To give an air of greater likelihood to this notion of his, he goes on to enumerate the changes which the semen, not yet emitted, but laid up in the testes and vesiculæ seminales of animals, occasions.

But besides the fact that all this does not bear upon the question, for the principal element under discussion is, not how the semen galli renders the egg prolific, but rather, how does the semen galli fashion and construct the chick from the egg? Almost everything he adduces in support of his view appears either false or open to suspicion, as is obvious, from the facts stated in our history; for neither is the blind cavity situated at the root of the uropygium or coccyx of the fowl, which he entitles “bursa,” destined as a receptacle for the semen of the cock, nor can any semen be discovered there, as we have said; but the cavity is encountered in the male as well as in the female fowl.

Our authority nowhere explains what he understands by a “spiritual substance,” and an “irradiation;” nor what he means by “a substance through whose virtue the egg is vivified:” he does not say whether it is any “corporeal” or “formal” substance, which by “irradiation” proceeds from the semen laid up in the bursa, and, (what is especially required,) constructs a pullet from the egg.

In my opinion, Fabricius does no more here than say: “It produces the chick because it irradiates the egg; and forms because it vivifies;” he attempts to explain or illustrate the exceedingly obscure subject of the formation of a living being by means still more obscure. For the same doubt remains untouched, how, to wit, the semen of the cock without contact, an “external efficient” at best, separate in point of place, and existing in the bursa, can form the internal parts of the fœtus in ovo,--the heart, liver, lungs, intestines, &c., out of the chalazæ by “irradiation.” Unless, indeed, our author will have it that all takes place at the dictum as it were of a creator seated on his throne, and speaking the words: Let such things be! namely, bones for support, muscles for motion, special organs for sense, members for action, viscera for concoction and the like, and all ordered for an end and purpose with foresight, and understanding and art. But Fabricius nowhere demonstrates that the semen has any such virtue, nowhere explains the manner in which without so much as contact the semen can effect such things; particularly when we see that the egg incubated by a bird of another kind than that which laid it, or cherished in any other way, or in dung, or in an oven, far from the bursa of the parent hen, is still quickened and made to produce an embryo.

The same difficulty still remains, I say: how or in what way is the semen of the cock the “efficient” of the chick? It is in no wise removed by invoking the irradiation of a spiritual substance. For did we even admit that the semen was stored in the bursa, and that it incorporated the embryo from the chalazæ by metamorphosis and irradiation, we should not be the less deeply immersed in the difficulty of accounting for the formation of all the internal parts of the chick. But these notions have already been sufficiently refuted by us.

Wherefore, in investigating the efficient cause of the chick, we must look for it as inhering in the egg, not as concealed in the bursa; and it must be such, that although the egg have long been laid, be miles removed from the hen that produced it, and be set under another hen than its parent, even under a bird of a different kind, such as a turkey or guinea-fowl, or merely among hot sand or dung, or in an oven constructed for the purpose, as is done in Egypt, it will still cause the egg to produce a creature of the same species as its parents, like them, both male and female, and if the parents were of different kinds, of a hybrid species, and having a mixed resemblance.

The knot therefore remains untied, neither Aristotle nor Fabricius having succeeded even in loosening it, namely: how the semen of the male or of the cock forms a pullet from an egg, or is to be termed the “efficient” of the chick, especially when it is neither present in, nor in contact with, nor added to the egg. And although almost all assert that the male and his semen are the efficient cause of the chick, still it must be admitted, that no one has yet sufficiently explained how it is so, particularly in our common hen’s egg.

EXERCISE THE FORTY-NINTH.

_The inquiry into the efficient cause of the chick is one of great difficulty._

The discussion of the efficient cause of the chick is, as we have said, sufficiently difficult, and all the more in consequence of the various titles by which it has been designated. Aristotle, indeed, recites several efficient causes of animals, and numerous controversies have arisen on the subject among writers, (these having been particularly hot between medical authors and Aristotelians,) who have come into the arena with various explanations, both of the nature of the efficient cause and of the mode of its operation.

And indeed the Omnipotent Creator is nowhere more conspicuous in his works, nowhere is his divinity more loudly proclaimed, than in the structure of animals. And though all know and admit that the offspring derives its origin from male and female, that an egg is engendered by a cock and a hen, and that a pullet proceeds from an egg, still we are not informed either by the medical schools or the sagacious Aristotle, as to the manner in which the cock or his semen fashions the chick from the egg. For from what we have had occasion to say of the generation of oviparous and other animals, it is sufficiently obvious that neither is the opinion of the medical authorities admissible, who derive generation from the admixture of the seminal fluids of the two sexes, nor that of Aristotle, who holds the semen masculinum for the efficient, and the menstrual blood for the material cause of procreation. For neither in the act of intercourse nor shortly after it, is aught transferred to the cavity of the uterus, from which as matter any part of the fœtus is immediately constituted. Neither does the “geniture” proceeding from the male in the act of union (whether it be animated or an inanimate instrument) enter the uterus; neither is it attracted into this organ; neither is it stored up within the fowl; but it is either dissipated or escapes. Neither is there anything contained in the uterus immediately after intercourse, which, proceeding from the male, or from the female, or from both, can be regarded as the matter or rudiment of the future fœtus. Neither is the semen galli stored and retained in the bursa Fabricii of the hen or elsewhere, that from thence, as by the irradiation of some spiritual substance, or by contact, the egg may be fashioned or the chick constituted from the egg. Neither has the hen any other semen save papulæ, yelks, and eggs. These observations of ours, therefore, render the subject of generation one of greater difficulty than ever, inasmuch as all the presumptions upon which the two old opinions repose are totally overthrown. The fact is especial, as we shall afterwards demonstrate, that all animals are alike engendered from eggs; and in the act of intercourse, whether of man or the lower quadrupeds, there is no seminal fluid, proceeding from the male or the female, thrown into the uterus or attracted by this organ; there is nothing to be discovered within its cavity, either before intercourse, during the act, or immediately after it, which can be regarded as the matter of the future fœtus, or as its efficient cause, or as its commencement.

Daniel Sennert, a man of learning and a close observer of nature, having first passed the reasonings of a host of others under review, approaches the subject himself; and concludes that the vital principle inheres in the semen and is almost identical with that which resides in the future offspring. So that Sennert does not hesitate to aver that the rational soul of man is present in his seminal fluid, and by a parity of reasoning that the egg possesses the animating principle of the pullet; that the vital principle is transported to the uterus of the female with the semen of the male, and that from the seminal fluids of either conjoined, not mixed (for mixture, he says, is applied to things of different species), and endowed with soul or the vital principle a perfect animal emerges. And therefore, he says, the semen of either parent is required, whether to the constitution of the ovum or of the embryo. And having said so much, he seems to think that he has overcome all difficulties, and has delivered a certain and perspicuous truth.