Superos quid quærimus ultrà?
Jupiter est quodcumque vides, Jovis omnia plena,—
other wise men fancied that they had actually discovered the seat of life, which, according to their fanciful speculations, they had lodged in certain organs. The nervous system, the spinal marrow, the brain, the heart, were all and each of them considered in turn as the head-quarters of vitality; while the workshop of alimentation, or much-abused stomach, did not pass unnoticed and unhonoured. The heart of a turtle, and of some reptiles, has been seen contracting and dilating hours after its extraction from the body; the stomach has been excited into an action bearing some analogy to vomiting, when separated from the trunk; but all these curious phenomena, explained and accounted for (in some measure, at least) by physiology, do not tend to prove that any one organ, or any chain of organs, is possessed of separate vitality independent of the general principle of life. The brain, which has been regarded as the chief seat of this principle, is not always essential to life; for although man perishes, or at least his vital functions cease to act, when he is decapitated,[30] yet various birds and reptiles continue to live for hours and days after the head has been severed from the body, while we actually behold a regeneration of the head in the earth-worm. Moreover, we have upon record many cases of acephalous children, or born without any head; and anencephalous children who lived (for a short time, it is true) without any brains. Fontana removed the entire brain of a turtle, yet it lived six months, and walked about as before.
Sandiford had divided acephalous animals into three classes: the first, in which the head was wanting; the second, where other organs were also missing; and the third, where the fœtus presented an unformed mass. In the acephalous twin described by Béclard, no liver, spleen, stomach, or œsophagus could be discovered, and the intestinal tube commenced at the superior extremity of the body. The infant had ten ribs on each side, and regular nerves arose from the spinal marrow. Although headless animals may not be gifted with intellectual faculties evident to our senses, yet they clearly live and feel. The zoophytes and polypes, without brains or heads, possess irritability and sensibility; they can seek their food, seize it, reject what is not edible, are susceptible of the powers of light and heat, can contract their fibres when touched or injured, and, in short, manifest various innate or instinctive powers. Gall has maintained that the passions resided in the brain, and, therefore, that brainless animals did not experience their influence. This is a bold assertion. Can he prove that worms, insects, zoophytes, that possess only what is called a ganglionic system, are strangers to instinctive fears and partialities? I apprehend that it will be found that passions belong to instinct much more than to our volition.
It is nevertheless true that animals may be killed by wounding the spinal marrow, by the process commonly called “pitting.” This practice may be traced to high antiquity; and Livy informs us that when the Carthaginian troops were routed, Asdrubal ordered their unmanageable elephants to be destroyed by driving the point of a knife between the junction of the head and spine.
From these observations it will appear quite clear that life has no necessary connexion with sensation, although the latter cannot be experienced without the former. Vegetables are endowed with vitality; but we have no reason to suppose that they feel. It is also more than probable that, as the degree of intelligence decreases, the intensity of the corporeal feelings are also diminished. Did not this scale of sensibility exist, insects could not live under the supposed agonies that the entomologist daily inflicts. This supposition does not rest upon indefinite reasoning, for in our own race we observe that those parts which are gifted with a reproductive power are possessed of the smallest degrees of sensation; and the cuticle, the hair, the beard, and the nails will even grow after death. This fact may calm the apprehensions of those very humane persons who look upon experimental physiologists as very monsters of barbarity. Vaillant took out the intestines of a locust, and stuffed it with cotton, then fixed it down in his box with a pin, yet, five months after, the insect moved its feet and antennas. Spallanzani has shown that the snail can renew its head.
All this confusion in theories and wandering of the imagination have arisen from our confounding the vital principle, of which we know nothing, with the phenomena of sensation, for which patient and calm investigation may account. That there does exist a principle of life that animates, vivifies, and preserves all living bodies, until its powers cease, no one can deny; although to find out its nature is a vain pursuit, as idle as our endeavours to penetrate into the causes of causation. As Richerand observes, “its essence is not designed to preserve the aggregation of our constituent molecules, but to collect other molecules, which, by assimilating themselves to the organ that it vivifies, may replace those which daily losses carry off, and which are employed in repairing and augmenting them; the word vital principle is therefore not designed to express a distinct being, but denotes the totality of powers alone which animate living bodies, and distinguish them from inert matter, the totality of properties and laws which govern the animal economy.”
Of all the doctrines upon this abstruse subject (of which I have noticed the principal ones), that of the pre-existence of an organic germ appears the most plausible, or at any rate the easiest to conceive. It was from this conviction that the ancients held as an axiomatic principle Omnia ex ovo. It is upon this theory that Buffon rested his organic molecules, and Ray his vital globules. The primitive lineaments of organization may be traced in the egg, even before it is fecundated. The embryo that we find in its involucra is soft, flexible, ready to receive the plastic impression of the vivifying secretion,—the fecundating agency that imparts existence and all its wondrous attributes, to the pre-existing ova, the ova subventanea. It does not appear that the first organ of the embryo which exhibits the living principle is the heart, hence denominated in the fœtus the punctum saliens; the principle of life has probably organized every molecule of the animal long before this supposed fountain of vitality had been seen to flow. It is more likely that the nervous system has received the first impressions imparted by the fecundating secretion, which the ancients supposed to have been a direct emanation from the brain, and bearing in its vivifying molecules the life of every part of the being it was about to organize; thus Valescus: “Sperma hominibus descendit ex omni corporis humore, qui fit ex subtiliori naturâ. Habet autem hoc sperma nervos et venas proprias attrahentes se à toto corpore ad testiculos—à membris disconditur principalibus—à corde, epate, cerebro mittuntur spiritus, ex quibus resultat spiritus informativus, et non aliter nisi cum spermate—ergo ab iis principaliter sperma disconditur.”
Such were the doctrines on this curious subject until the days of Fabricius d’Acquapendente and Harvey. Buffon, however, exerted all his eloquence to revive the theory. The following are the notions of this elegant writer, who unfortunately only studied natural history in books and cabinets. He maintains that there exist two sorts of matter,—the one living, the other dead: the first enjoying a permanent vitality; the second universally spread, passing from vegetables to animals through the channels of nutrition, and returning from animals to vegetables through the medium of putrefaction,—thus in a constant state of circulation to animate living beings. This vital matter exists in determined quantities in nature, and is composed of an infinity of organic molecules, primitive, living, active, incorruptible, and in relation, both as regards action and numbers, with the molecules of light, and enjoying an immutable existence, since the usual causes of destruction can only affect their adherence. It is these molecules which, being cast in regular moulds, constitute all the organized bodies that surround us. According to this doctrine, development and growth are only a change of form operated by the addition of organic molecules; nutrition, the preservation of this form by the accession of fresh molecules that replace those that are destroyed; generation, the combination of these particles; and death, their separation from cohesion and association.
This ingenious system is not dissimilar to that of Maupertuis, who thought that the mysteries of generation could be explained by the usual laws of elective attraction. Various were the physical, metaphysical, and moral batteries raised against this visionary fabric. One single fact was sufficient to overthrow it. We constantly see parents deficient in a limb, or misshapen, producing perfect offspring; if each part of the economy was to transmit to its progeniture molecules similar to itself, the child would naturally be visited with the imperfection of the parent.
Notwithstanding these fallacies, we cannot but admit that chemical and molecular attraction constitute the principle that harmonizes all organized bodies. Generation is simply a function of organization and life. Organized bodies alone can generate. The living only can impart life. Animals and plants transmit to their descendants their several properties; and the inheritance of organization departs with the vital spark. Life is the property of no one; it is a transmitted heir-loom that never perishes; it resembles a torch that communicates an eternal flame while consuming itself. Organized beings have justly been considered the fuel of the universal vital fire, and we all are the daily bread of that monstrous animal called the world. All are ingulfed in that vortex which Beccher has called the “circulus æterni motus” Metempsychosis was simply an illustration of this fact recognised in all ages in the East, and taught in European schools by Pythagoras. Nothing perishes; and even combustion produces fresh combinations.