Part 14

The head is clothed with luxuriant _hair_, composed of a multitude of individual fibres, each of which is an epidermic appendage, essentially similar to the nails. Every hair is contained at its basal extremity in a delicate follicle, where it terminates around a soft vascular bulb, made up of blood-vessels and nerves. On the surface of this living bulb the horny substance is continually secreted and deposited in layers, each of which in succession pushes forward those previously made, till the tip extrudes from the follicle of the skin, after which it continues to grow in the same way, as an external hair. The tip is gradually worn away; and thus the constant growth cannot, in general, cause it to exceed a certain given length. Each of the thousands of hairs with which this majestic head is clothed, bears witness to past time; and as the increase of hair is about an inch per month, and as this hair is about four inches in length, we have here thousands of witnesses to at least four months of previous history.

The bones which make up the firm and stately fabric about which this human body is built, are no productions of a day. Long before this they existed in the form of cartilages. In these, minute arteries began to deposit particles of phosphate of lime, around certain centres of ossification, doing their work in a determinate order, and in regular lines, so as to form continuous fibres. These fibres, aggregated, and connected by others, soon formed a texture of spicula or thin plates.

Now take as an example a cylindrical hollow bone, as that of the thigh. Here the spicula were arranged longitudinally, parallel to the axis of the bone: preserving the general form of the cartilage which constituted its scaffolding.

But the bone required a progressive increase in size. In its early state, moreover, it was not hollow, but solid. Changes must have taken place to bring it to its present dimensions and condition. These were effected by the actual removal of some parts, simultaneously with the deposition of others.

At a certain stage of ossification, cells were excavated by the action of the absorbent vessels, which carried away portions of bony matter lying in the axis of the cylindrical bone. Their place was supplied by an oily matter, which is the marrow. As the growth proceeded, while new layers were deposited on the outside of the bone, and at the end of the long fibres, the internal layers near the centre were removed by the absorbent vessels, so that the cavity was further enlarged. In this manner the outermost layer of the young bone gradually changed its relative situation, becoming more and more deeply buried by the new layers which were successively deposited, and which covered and surrounded it; until by the removal of all the layers situated near to the centre, it became the innermost layer, and was itself destined in its turn to disappear, leaving the new bone without a single particle which had entered into the composition of the original structure.[87]

These processes have been the slow and gradual work of years, of the lapse of which years the bones are themselves eloquent witnesses.

Within the mouth there are many _teeth_. I will not now speak of their exact number, nor of some other particulars concerning them, because I mean to return to them presently; but I look only at their general structure and origin. Each tooth consists of three distinct parts, the central portion, which is _ivory_; the exceedingly hard, polished, glassy coat of the crown, which is _enamel_; and a thin layer of bone around the fang, which is the _cement_.

Before either of these appeared, a minute papillary process of vascular pulp was formed in a cavity of the jaw. Over the pulp was spread an excessively thin membrane, which secreted from the blood, and deposited, a thin shell of bony matter, or ivory, moulded on the form of the pulp. Successive layers of ivory were then added, from within; the pulp diminishing in a corresponding ratio. The cavity of the jaw at the same time deepened, and the pulp lengthened downward into the space thus provided; layers of bony substance being gradually deposited upon it, as above.

The cavity itself was lined with a thick vascular membrane, united to the papilla at its base. Within the space lying between this membrane and the pulp, there was deposited from the wall of the former a soft, granular, non-vascular substance, known as the enamel organ. The cells on the inner surface of this substance then took the form of long, sub-parallel prisms, set in close array, perpendicular to the surface of the tooth. Earthy matter was progressively deposited in them, by which they became the exceedingly dense and hard enamel of the crown. The cement of the fang was then formed by a slight modification of the process which had produced the enamel.

Here, then, are several distinct and important processes, effected in regular and immutable succession, each requiring time for its performance, and all undeniably witnessed-to by the structure of every tooth here seen.

As I have thus proved the _fact_ of life existing in this human body for some time previous to the present moment, I now proceed to inquire how far its structure may throw light on the _actual duration_ of that past life. How far can we ascertain its chronology?

The stature of the Man before me is about six feet. An infant at birth is from eighteen to twenty-one inches in length. At ten years old the average stature is about four feet. Six feet may be taken as the full adult height of man; and this is attained from the twenty-first to the twenty-fifth year. The stature of this individual would therefore indicate an age not less than twenty-one years.

On the front of the throat I perceive a strongly-marked, angular prominence, formed by the union of the two plates of the thyroid cartilage. The prominence of this angle is due to the enlargement of the larynx; and it is accompanied by a deepening of the pitch of the voice, producing the full rich sounds that we have this instant heard, as the Man chanted his song of praise. These tones, and this projection of the thyroid cartilage, are equally distinctive marks of puberty, and do not appear till about the sixteenth or seventeenth year.

The chin, and sides of the face, are clothed with a dense bush of crisp hair,--the beard. This is a distinctive mark of the adolescent period, and may be taken as indicating an age not less than twenty years.

On again examining the mouth, I find the teeth are thirty-two in number; viz., four incisors, two canines, four pre-molars, and six true molars, in each jaw. None of these existed (at least visibly) during the first seven years of life; in that period they were represented by the milk-teeth of infancy. The appearance of the middle pair of incisors occurred at about the eighth year; the lateral incisors at nine; the first pre-molars at ten; the second at eleven; the canines at about twelve; the second molars at thirteen or fourteen; and the third molars, or _dentes sapientiæ_, at about seventeen or eighteen.

The state of the dentition, then, points to an age certainly not less than the period just named. How much more it may be, we must gather from other sources.

I come now to certain phenomena which are not appreciable to us on mere external examination; but which I am able with certainty to predicate. And the first of these is the proportion of arterial to venous blood in the capillaries. In infancy, the arterial capillaries contain far more blood than the capillary veins; in old age, the proportion is exactly reversed; whereas, in maturity, the ratio is just equal. Now, here there is a very small preponderance of arterial blood, indicating a period but slightly remote from maturity on the side of youth; well agreeing with the conclusion arrived at from previous premises, of some twenty to five-and-twenty years.

Other and more marked manifestations occur in the condition of the skeleton. In the spine, I find _the spinous and transverse processes_ of the several vertebræ are completed by separate _epiphyses_, the ossification of which does not commence till after puberty, and the final union of which with the body of the bone does not occur till about the age of twenty-five years.

Each _vertebra_, moreover, has attained a smooth annular _plate_ of solid bone, covering a surface that was previously rough and fissured, which is invariably added at the same period.

The _ossification of the sacrum_ also has reached its culminating point. At the age of puberty, the component vertebræ began to unite from below upwards, and the two highest have now coalesced; which also marks a period of life not earlier than the twenty-fifth year. The whole united mass, moreover, is furnished on each side with thin bony plates, the appearance of which is no less characteristic of the same age.

Each of the _ribs_ is here furnished with two _epiphyses_, one for the head and the other for the tubercle; the ossification of these began soon after puberty; but their union with the body of the bone, as presented here, has taken several years to accomplish.

To come to the limbs, we find the _shoulder-blade_ presenting three _epiphyses_, one for the _coracoid_ process, one for the _acromion_, and one for the lower angle of the bone, the ossification of which begins soon after puberty, their union with the body of the bone taking place between the ages of twenty-two and twenty-five years. The _clavicle_ has an _epiphysis_ at its sternal end, which begins to form between the eighteenth and twentieth years, and is united to the rest of the bone a few years later. The consolidation of the shoulder-bone (_humerus_) is completed rather earlier; the large piece at the upper end, which is formed by the coalescence of the ossific centres of the head and two tuberosities, unites with the shaft at about the twentieth year; whilst its lower extremity is completed by the junction of the external condyle, and of the two parts of the articulating surface (previously united with each other), at about the seventeenth year, and by that of the internal condyle in the year following. The superior _epiphyses_ of the arm-bones (_radius_ and _ulna_) unite with their respective shafts at about the age of puberty; the inferior, which are of larger size, at about the twentieth year. The _epiphyses_ of the _metacarpal_ and _phalangeal bones_ (those of the hand and fingers) are united to their principals at about the twentieth year. In the _Lower Extremities_, the process of ossification is completed at nearly the same periods as that of the corresponding parts of the Upper. The consolidation of the hipbones (_ilium_, _ischium_, and _pubis_) to form the _os innominatum_, by the ossification of the triradiate cartilage that intervenes between them in the socket of the thigh (_acetabulum_), does not take place until after the period of puberty; and at this time additional _epiphyses_ begin to make their appearance on the crest of the _ilium_, on its anterior inferior spine, on the tuberosity of the _ischium_, and on the inner margin of the _pubes_, which are not finally joined to the bone until about the twenty-fifth year.[88]

The concurrence of these conditions in the skeleton, the nearly balanced ratio of the bloods, the perfected dentition, the beard, the deepened voice, the prominent larynx, and the stature, combine to point out, with infallible precision, the age of this Man, as between twenty-five and thirty years.

So far, then, we can with certainty trace back the history of this being, as an independent organism; but did his history then commence? O no; we can carry him much farther back than this. What means this curious depression in the centre of the abdomen, and the corrugated knob which occupies the cavity?[89]

This is the NAVEL. The corrugation is the cicatrice left where once was attached the umbilical cord, and whence its remains, having died, sloughed away. This organ introduces us to the foetal life of Man; for it was the link of connexion between, the unborn infant and the parent; the channel, through whose arteries and veins the oxygenated and the effete blood passed to and from the parental system, when as yet the unused lungs had not received one breath of vital air.

And thus the life of the individual Man before us passes, by a necessary retrogression, back to the life of another individual, from whose substance his own substance was formed by gemmation; one of the component cells of whose structure was the primordial cell, from which have been developed successively all the cells which now make up his mature and perfect organism.

* * * * *

How is it possible to avoid this conclusion? Has not the physiologist irrefragable grounds for it, founded on universal experience? Has not observation abundantly shown, that, wherever the bones, flesh, blood, teeth, nails, hair of man exist, the aggregate body has passed through stages exactly correspondent to those alluded to above, and has originated in the uterus of a mother, its foetal life being, so to speak, a budding out of hers? Has the combined experience of mankind ever seen a solitary exception to this law? How, then, can we refuse the concession that, in the individual before us, in whom we find all the phenomena that we are accustomed to associate with adult Man, repeated in the most exact verisimilitude, without a single flaw--how, I say, can we hesitate to assert that such was his origin too?

And yet, in order to assert it, we must be prepared to adopt the old Pagan doctrine of the eternity of matter; _ex nihilo nihil fit_. But those with whom I argue are precluded from this, by my first Postulate.

XI.

PARALLELS AND PRECEDENTS.

(_Germs._)

"Every cell, like every individual Plant or Animal, is the product of a previous organism of the same kind."--(DR. CARPENTER, _Comp. Physiol._ § 347.)

In the preceding examples I have assumed that every organic entity was created in that stage of its being which constitutes the acme of its peculiar development; when all its faculties are in their highest perfection, and when it is best fitted to reproduce its own image. From the very nature of things I judge that this was the actual fact;[90] since, if we suppose the formation of the primitive creatures in an undeveloped or infant condition, a period would require to lapse before the increase of the species could begin; which time would be wasted. To those, indeed, who receive as authority the testimony of the Holy Scripture, the matter stands on more than probable ground; for its statements, as to the condition of the things created, are clear and full: they were not seeds, and germs, and eggs, and embryos,--but "the tree yielding fruit whose seed was in itself,"--"great whales,"--"winged fowl,"--"the beast of the earth,"--and "man."[91]

But I do not mean to shield myself behind authority. I have begged the _fact_ of creation; but not the truth, nor even the existence, of any historic document describing it. It is essential to my argument that any such be left entirely out of the question; and, for the present, I accordingly ignore the Bible.

It is possible that some opponent may object to my assumption of maturity in created organisms.

"Your deductions may be sound enough," such an one may say, "provided your newly-created Locust-tree had so many concentric cylinders of timber, your Tree-fern had a well-developed stem of leaf-bases, your Coral a great aggregation of polype-cells, your Tortoise a carapace of many-laminated plates, your Elephant a half-worn set of molars, and your Man a thoroughly ossified skeleton. But how do you know that either of these organisms was created in this mature stage? I will not deny that each was created,--was called suddenly out of non-entity into entity; but I believe, or at least I choose to believe,--that each was created in the simplest form in which it can exist; as the seed, the gemmule, the ovum, the--ahem!"

Pray go on! you were about to say "the infant," or "the foetus," or "the embryo," probably; pray make your selection: which will you say?

"Well, I hardly know. Because, if I choose the new-born infant, you will say, Its condition implies a nine months' pre-existence, certainly; not to speak of the absurdity of a new-born infant being cast out into an open world without a parent to feed it. If I say, The foetus, or the still more incipient embryo, I involve, at once, a pre-existent mother. I am afraid you have me there!"

I think I have. However, let us take up the matter orderly, and proceed on the supposition that my previous examples must be all cancelled, and the question argued _de novo_, on the assumption that each organism was created in its least developed condition.

It will not be considered necessary, I suppose, to look at any intermediate condition of the organisms. The argument which is based upon the leaf-scales of the Fern or the Palm would essentially apply to either of these plants when it first issues from the ground. At the period when it comprises but a single frond, the botanist would no more hesitate in pronouncing that the organism had passed through stages previous to that one, than he would when it possesses an elongated stipe; though, in the latter case, the evidences of the pre-existence are more patent to the uninstructed eye. He would say, The single frond implies, with absolute necessity, a spore in the one case, a seed in the other; and we need not to see either, to be assured that this must have preceded the leaf-stage.

But you go farther back still. "The plant was created as a seed." Let us renew our imaginary tour at the epoch, or epochs (as many as you please), of creation, on this supposition.

Here is a very young plant of the curious Seychelles Palm or Double Cocoa-nut (_Lodoicea Sechellarum_). A single frond is all that is yet developed, and this is as yet unexpanded, the pinnæ being still folded on the midrib, like a fan. Trace the frond down to its base. It springs from a thick horizontal cylindric process, which has also shot down a radicle into the soil. We trace the cylindrical stem along the surface of the soil, and find, lying on the ground, among the grass, but not buried, a great double nut, something like the two hemispheres of a human brain, or like a common cocoa-nut, half split open and healed. Out of this the thick stem has issued; and we find that it is only the cotyledon of the seed, that has prolonged its base in the process of germination, in order to throw up, clear of the nut, the plumule and radicle.

We look at the great nut, and find, on the woody exterior of the fibrous pericarp, at the side opposite to that whence issues the cotyledon, a broad scar. What is this? It is the _mark left by the severance of a footstalk_, which united the fruit to the parent plant. This great drupe was once a small ovary seated in the centre of a three-petaled flower, which, with many others, issued out of a great spathe, a mass of inflorescence, and hung down from the base of the leafy coronal of an adult palm-tree. This scar is an irreproachable witness of the existence of the parent palm.

Here, lying on the dry and dusty earth, is a brown flat bean of great hardness. This is a seed destined by and by to produce that splendid tree _Erythrina crista-galli_. But it has been just created.

This bean bears on one of its edges an oval scar, very distinctly marked, called the _hilum_. This was the point of attachment of a short column, by which the seed was united to one of the sutures of a long pod, in the interior of which it lay, in company with several others like itself. This great legume or pod had been the bottom of the pistil of a papilionaceous flower, crowned by a tiny stigma, lodged in a sheath formed by the united stamens, and surrounded by a corolla of refulgent scarlet petals.

Of course such a flower was not an independent organism; it was one of many that adorned a great tree, the history of whose life would carry us back through several generations of human years.

This single infolding leaf, that is just shooting from the soil, so small and feeble,--what of this? There are certainly no concentric cylinders of timber here: can we trace a previous history of this?

Yes: by carefully removing the soil from the base, we see that it originates in a flat yellow seed--the seed of a Tulip. Here again we have no difficulty in detecting evidence of its former attachment. A great number of these seeds were once closely packed one on another, in each of the three carpels that constituted the capsule. And this capsule had been the oblong, three-sided ovary, which formed the body of the pistil in some beautiful Tulip.

Do you observe these two round fleshy leaves, just peeping from the sandy earth? They are the earliest growths of a plant of _Arachis hypogæa_. In this case again, to understand the true relations of this organism, we must expose it wholly to view.

Beneath the surface of the earth, then, I find that these seed-leaves are the two halves (_cotyledons_) of a kind of pea, which was formerly enclosed in a wrinkled skinny pod. But what is most interesting is that the pod is here, the cotyledons shooting out of it. And, attached to one end of the pod, here is a slender stalk, now withered and dry, which projects out of the ground into the air.

Now here we have a beautiful link of connexion with the past. The plant before us does not ripen its seeds, and then drop them to care for themselves, as most plants do. "The young fruit, instead of being placed at the bottom of the calyx, as in other kinds of pulse, is found at the bottom and in the inside of a long slender tube, which looks like a flower-stalk. When the flower has withered, and the young fruit is fertilized, nothing but the bottom of the tube with its contents remains. At this period a small point projects from the summit of the young fruit, and gradually elongates, curving downwards towards the earth. At the same time the stalk of the fruit lengthens, until the small point strikes the earth, into which the now half-grown fruit is speedily forced, and where it finally ripens in what would seem a most unnatural position."[92]

The young plant before us has been this moment created, and created in this incipient stage of growth: and yet there is, even here, an indubitable evidence, so far as physical phenomena can afford it, of a past history. It would be utterly impossible to select any stage in the life of the Earth-pea, which did not connect itself, visibly and palpably, with a previous stage.

Let us return to the shore-loving Mangrove. You object to my assumption that it was created as a tree, with a well-branched stem elevated upon a series of arching roots; and to my deduction of pre-lapsed years for the formation of those roots. Very well. I give it up. You allow that the primitive Mangrove was created in some stage, but you contend for the germ-stage, the simplest condition of the plant, whatever that might be.

Now, where shall we find it? In the first pair of developed leaves? They certainly point back to the cotyledons. To the cotyledons, then, let us look.