That life is tremulation, or that whatever is living in us must be expressed by the motions of tremulation, is manifest not only from the connection of every least part, but especially from this fact, that life has a tendency to accommodate itself altogether to the solidity in the systems of the body. For it was shown above that tremulation requires not only a tension, but also what is hard or solid, in order to effect an intensification of the sensation as well as a communication, just as a musical chord requires a hard and concave body, which effects the reverberation of the sound as well as the aptitude of the chord for tremulation; otherwise the vibration of the chord would hardly reach the tympanum of the ear, but would vanish in the folds of the external organ. It is hardness or solidity, therefore, that contributes a higher degree of the perception of tremulation, or which makes us conscious of the sensation, as may be seen from the whole life of man, in all its ages.
Consider the state of a new-born infant: there is nothing fixed or stable in his whole body, no firmness in any bone; the cranium legends to the touch of the finger; there is no consistency in Shoulder or leg; the dura mater has not yet become fixed to its sutures; that which is to become hard is still a serum or a yielding substance, so that no tremulation is as yet able to pass from what is soft to what is hard, or vice versa, to effect a sensation; the meninges of the head lie on a very soft cerebrum; the arteries or other vessels have not yet fixed themselves firmly to their canaliculi so as to prepare the membranes for the reception of tremulation; the cerebrum itself is not able to contribute any expansion or tension to its tunics, but must, like a mere fluid, leave with the matres whatever impression is made upon them. Here we may see, as in a picture, how life, and the use of the senses, must accommodate itself to what is hard, and how all the tremulations are kept back on account of the absence of this hardness. The external senses are not yet fully alive with the new-born infant; he can perceive nothing distinctly; hearing, sight, and all the rest, are to him like a shadow or a cloud, in which nothing distinctive is possible. The cranium being soft, the membranes have not as yet gained any proper expansion, have not been attuned, as it were, but are like loose strings, over which a tremulation may indeed pass, but only with an undulatory and dull motion, without producing distinct sounds, and without power to reach the bridge of the instrument by any other natural motion than the involuntary one.
But the compositions in the body soon begin to gain stability, fixedness, and expansion; the sutures of the skull are gradually closed and knit together, thus drawing the membranes toward the cranium; the nerves also grow harder because the medullary or striated part in the greater nerves is drawn into hard filaments on which the membranes of the nerves lie as on hard bottoms. Life then begins to become properly living, the senses receive their alertness and acumen, everything gains more and more knowledge of its own use and quality. In a word, nature then begins to express itself, the sensories find their termini, and the tremulation gains freedom to pass from ultimate things to inmosts.
Passing by the years of growth, when the various bodily systems are continually adding something to their size and hardness, we arrive at Adult Age, when the efflux of the nervous fluid becomes proportioned to the expanse of the body, so as to give it sufficient nutriment, or when the medulla is fully able to support the full-grown bones and body. our whole system of bones has then become fixed and has gained its proper dimensions and hardness; everything is firm and living; all the senses are in the fulness of their uses, and the internal senses, such as the memory and the thought, are at their highest point of development. The membranes, also, are then most firmly expanded by their vessels, such as the arteries, veins, and lymphatic ducts; the medulla has been shaped into long striae; the nerves have become firm; the bones and the cranium have fully developed their porosity; and the lamina of the bones have gained their hardness, so that tremulations may be properly received. Since now it may be seen that the tremulatory motions effect a better sound or sensation by means of tension or hardness than by the contrary, we have also proved that life, or what is properly living in us which is a distinct perception or discrimination of all things consists in tremulations. For when the compaginations or systems, over which the tremulation is to pass, are out of their order and use through any improper softness, then also is all perception suffering, but as soon as the frame-work is ready, and the whole key-board furnished with taut strings, then only is it able to convey the sound or the perception, which propels itself by means of tremulations.
Now when Old Age comes on and inclines toward the end of life, the condition of the membranes and of the who]e frame is equally notable. The medullary substance, both in the spine and in the cerebrum, is then becoming more and more hard and sinewy, for its whole tendency is to run into sinews. It has also been found that the medulla is more empty of its fluid with the aged than with the young, whence, with the former, the nerves no longer receive their proper nutriment; the fluid flows more sparingly to the membranes and the extremities; the serum and the Iymph become more and more dried up, making the matres more and more slack, wrinkled, and foiled; the finest bloodvessels can no longer penetrate to the surface, but are closed off by the hardening external forms, are kept away from their most subtle ducts, and thus cause the meninges and all the other cuticles to fall into folds and wrinkles; everything is becoming more and more empty and light, and man is failing as to every part. It may thus be seen how the tremulation is as it were shut off from effectingb the life of the senses; the membranes, over Which the motion is to pass, have become displaced, loosened, and slackened; the tremulation must needs stop at the first initiative, or it runs forward in a dull manner, almost without any sound; the acuteness of the sight as well as of the hearing decreases and becomes obscure, the membranes of the eye contracting to the injury of their convexity. Everything is more languid, slow, and tepid than before. The internal senses are similarly decreasing, accommodating themselves exactly to the condition of the membranes which now are slack and Wrinkled; all this a proof that the veriest life of man begins to fade away as soon as the tremulation is in any manner prevented.
Compare now what has been said above with the life of the higher animals, and it will be seen still more plainly that tremulation makes the greater part of our living force, and, in fact, takes the role of nature itself in our life. Such animals as are born with the bony system perfectly developed, or nearly so, come quickly into the use of their full nature, as a native or innate thing. A chickened for instance, possesses most of the consistency of its whole skeleton when it is first hatched out of the egg; it can walk, it can see, it can hear, and move its wings and neck; in a word, everything within it is at once attuned for the reception of tremulation. There is, therefore, nothing dull With this little creature, but it runs at once into the full enjoyment of its very nature, without having to be nursed for any length of time. Of the greater animals, some attain their full growth in a few weeks, some in a few months, the largest in three or four years, after which their senses are developed as perfectly a~h us when we have reached adult age. Everywhere it may be seen how nature accommodates itself to the firmness or hardness of the nerves and the bones.
Now if the life of the senses were effected by any other means than tremulation by--some volatile force, for instance--why is it that this must still be connected with a hardness in the bones and the membranes, as a necessary condition? Could not this force flow through a soft substance, or liquid, just as well, or better, than through what is hard? Why must the hardness open the door and prepare the way? Or why should not the same way be just as open with the aged as with the young? It is not clear that much traversing must open the channels wider and wider, and that, therefore, according to such hupothesis, all the senses must be more wide awwake with the very aged? But as it has been shown that everything of life is accomadated to the stiffness and tension of the membranes and to the hardness of the bones, we cannot form any other conclusion than that of the sensories, which are amalogous to these parts, and that the tremulatory motion, by this means, displays its real nature in its greater or lesser degrees.
But lest any one should think that the senses thamselves might be fully developed with the new-born infant, and that he is simply unable to give an expression to his sensations, we will point to this wonderful fact, that the whole of that period during which the meninges, with all the other coats and membranes, are soft, is a period of oblivion, from which the infant is utterly unable to retain consiously the least impression for a subsequent period of life. Whatever may have been effected by the senses during infancy, seems to have been erased with the youth; the most important impressions and experiences, and the most common habits of life, recieved and attracted during infancy, and afterwards retained in the organs of the nerves as the very nature of the child--all this remains in the memory less consciously than a dream, although, as was said, nature still retains it in the sensories as the initiament of life. As an illustration let us consider only the faculty of speech. During the period of oblivion the organism of the mouth has been taught by a variety of things how to strain forth the sounds by different vibrations, and how to articulate the words; everything that the nurse has done for the infant remains with him, but the first efforts and the original habituations are afterwards forgotten. That which became a habit has now become nature itself, and it effects the speech in a moment without the least trace of the original effort. We may therefore conclude that all such things consist of most subtle tremulations which derive their life from the hardness and tension of the vessels and organs; but as soon as these qualities are lost, the recollection begins to vanish, as with the very aged and decrepit, and with others in whom the dura mater has become greatly disordered.
It is, indeed, most wonderful that a man excels all animals chiefly in this, that he reaches his maturity later than they, and that the very thing which may be accounted his imperfection is really the chief means for his perfection, and for his exaltation above all animals. Besides being gifted with a Soul in a reasonable understanding, we have been so ordered by God that all our membranes and bones must require a long period in order to become fixed and hard. In the meantime all our organs are disposed for the reception of ever new impressions, all of which require their time, until we have reached adult age. Hence also we may see what an advantage there is in our approaching slowly to our maturity, namely, that the understanding is able to increase and be more and more perfected, so as finally to present a man who can exhibit a ripe understanding, built up by a multitude of impressions and experiences. An animal, on the other hand, attains the full nature of its parents after a very short period; its membranes and bones become fixed in that nature which has been produced by the impressions of its entire breed or race, and there is soon an end to all further increase.
I know, however, that many may make this objection, that even those membranes which cover the soft parts, and which are not expanded like drums, are still able to cause sensations and to transmit tremulations; and that a tremulation in the bones can effect the same, when yet these possess nothing sensitive. But to this objection I would answer, that I do not at all mean to say that tremulation is distributed over a membrane merely as a membrane, but only in the degree that the membrane is expanded by a fluid; and, further, that a tremulation in the bones does not effect a sensation merely as a movement in the bones, but simply that the latter communicate a tension and a tightening to the periosteum and the membranes, and these, consequently, to the lymphatic canaliculi. For the first tremulation strikes the fluid part, the contiguity of which causes the motion to run over all that is fluid within all the membranes and meninges; and as there are continuous valvuli, it follows that the tremulation, while on the way, strikes against all of these, whence it is carried into the membranes, and so from the latter into the bones, in which a stiffness and hardness are necessarily required. For if there is nothing hard to contribute a tension to the membranes, it follows that the latter must remain slack and unstrung, whence the tremulation cannot run through the lymphatic canaliculi in any proper manner, but must pull and twist the membranes, to the hindrance of the communication. It may be seen from this what the hardness in the bones and the tension in the membranes contribute to the liveliness of the motion in the lymphatic system.
"The contribution of Vibratory Transmission to Neuronal Transmission"
by Becky Chesire and Leon Jakobovits
American Psychology., 1986, in press