IMPERFECTION OF THE STUDY OF ANIMALITY.

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tinction between voluntary and involuntary motions arises. from no radical difference of muscular irritability, but only from the mode, and perhaps the degree of innervation, modified by long habit. If this be as generally true as it seems to be in some cases of acquired control, it must be supposed that the most involuntary motions, which are those most indispensable to life, would have been susceptible of voluntary suspension (not even excepting the motions of the heart) if their incessant rigorous necessity had not hindered the contraction of suitable habits in their While we conclude it to be probable that the difference between the two kinds of motion proceeds indirectly from the action of the entire nervous system upon the muscular system, we cannot help perceiving how greatly science stands in need of a thorough new examination into this obscure fact.

case.

This brief survey shows us the general Present state imperfection of the study of animality. We of analysis of shall find that even in the department of the animality. primitive analysis of its general phenomena, in which it appears so superior to that of the organic life, it is very far indeed from being yet fit for exploration by positive laws.

Movement.

In regard to irritability, first, the mechanism of no animal movement has yet been satisfactorily analysed, all the chief cases being still the subject of radical controversy among equally qualified physiologists. We retain a vicious distinction among movements, contrary to all mechanical judgment,—a distinction between the general motion which displaces the whole mass, and the partial motions which subserve the organic life,—as for the reception of aliment, or the expulsion of any residuum, or the circulation of fluids; yet the first order are partial, though their object is unlike that of the second; for, in a mechanical view, the organism allows of no others. By the great laws of motion, the animal can never displace its centre of gravity by interior motion, without co-operation from its environment, any more than a steam-carriage which should work without friction on a horizontal plane, turning its wheels without result. The movements which produce locomotion are not

mechanically different from those, for instance, which carry food along the alimentary canal ;-the difference is in the apparatus, which, for locomotion, consists of exterior appendages, so disposed as to cause a reaction in the medium, which produces the displacement of the whole body. Certain mollusks furnish an illustration of this, when they change their place by means of contractions of the cardiac muscle, or of intestinal muscles. The simplest notions of animal mechanics being thus obscured and corrupted in their origin, it is no wonder that the physiologists still dispute about the mechanism of the circulation, and most of the means of locomotion, as leaping, flying, swimming, etc. In the way in which they proceed, they are remote from any mutual understanding, and the most opposite opinions may be maintained with equal plausibility. It needs but a word to suggest to those who have attended to what has gone before, that this extreme imperfection results from the inadequate and faulty education of physiologists, who are too often ignorant of the inorganic science which is here directly involved. The complexity of the animal apparatus, and the impossibility of bringing the primitive moving powers under any mathematical theory, will for ever forbid the application of numerical methods: but the great laws of equilibrium and motion are applicable, through all varieties of apparatus, and are the same in animal mechanics, or celestial, or industrial, or any other mechanics whatever. Some physiologists, finding their difficulty, have handed over their study to the geometers and physicists: and these, with their habits of numerical precision, and their ignorance of anatomy, have brought out only absurd results. The remedy is, as we know, in the work being consigned to physiologists, duly prepared by a sufficient training in inorganic science. The study of animal sounds, or phonation, for instance, cannot be carried on to any purpose without such knowledge as physicists have of the theory of sound; and the general production of the voice, and the differences of utterance among animals, require for their explanation a knowledge at once of acoustics and anatomy; and speech itself requires this preparation no less, while demanding other requisites with it. It is to be hoped that all experience, in each

department of scientific inquiry, will convince students more and more of the folly and mischief of the anarchical parcelling out of natural philosophy; but the physiologists are those who. above all, must see the need of a better organization of scientific labour,—so remarkable as is the subordination of their particular science to all that have gone before.

:

Exterior sen

sation.

The analysis of the phenomena of sensibility is not more satisfactory than that of irritability and even less so, if we leave out of the account the great knowledge that we have obtained, by anatomical study, of the corresponding organs; a knowledge which, however, must here be connected with physiology. The least imperfect part of this study relates to the simple exterior sensations. The phenomenon of sensation is composed of three elements, as we have seen: the impression of the external agent or the nervous extremities, by the aid of some physical apparatus; the transmission by the nervous fibre; and the reception by the cerebral organ. The first of these suggests, like the mechanical facts we have been considering, the immediate dependence of the phenomenon on the laws of the inorganic world; as the relation of the theory of visions to optics of the theory of hearing to acoustics, in all that concerns the mode of action proper to the apparatus of sight and hearing. And yet, more expressly than even in the case of mechanics, have these theories been delivered into the hands of the physicists, who, again, bring out results from their treatment of them which are manifestly absurd. The only difference between this case and the preceding is that the metaphysicians have kept a longer bold upon this part of animal physiology, the theory of sensations having been abandoned to them till a very recent time. It was not, indeed, till Gall imparted his evermemorable impulse to the investigation, that physiologists claimed this department at all. It is no wonder, therefore, that the positive theory of sensations is less well conceived, and more recent, than that of motion; and naturally more imperfect, independently of its superior difficulty, and the backwardness of those branches of physics to which it relates. The simplest modifications of the phenomenon of

vision and of hearing cannot as yet be referred with certainty to determinate organic conditions; as, for instance, the adjustment of the eye to see distinctly at very various distances; a faculty which the physiologists have allowed the physicists to attribute to various circumstances of structure, always illusory or inadequate, the physiologists the while playing the part of critics, instead of appropriating a study which belongs exclusively to them. Even the limits of the function are usually very vaguely defined: that is, the kind of exterior notions furnished by each sense, abstracted from all intellectual reflection, is rarely circumscribed with any distinctness. Thus it is no wonder if we are still ignorant of almost all positive laws of sight and hearing, and even of smell and taste.-The only point of doctrine, or rather of method, that we may consider to have attained any scientific stability, is the fundamental order in which the different kinds of sensations should be studied and this notion has been supplied by comparative anatomy rather than by physiology. It consists in classifying the senses by their increasing speciality,-beginning with the universal sense of contact, or touch, and proceeding by degrees to the four special senses, taste, smell, sight, and finally, hearing. This order is rationally determined. by the analysis of the animal series, as the senses must be considered more special and of a higher kind in proportion as they disappear from the lower degrees of the zoological scale. It is remarkable that this gradation coincides with the degree of importance of the sensation in regard to sociality, if not to intelligence. Unhappily, it measures yet more evidently the increasing imperfection of the theory. We ought not to pass over the luminous distinction introduced by Gall between the passive and the active state of each special sense. An analogous consideration to this, but more fundamental, would consist, it seems to me, in distinguishing the senses themselves as active and passive, according as their action is, from their nature, voluntary or involuntary. This distinction seems very marked in the case of sight and hearing; the one requiring our free participation, to a certain extent, while the other affects us without our will, or even our consciousness. The more vague, but more profound influence that music

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exercises over us, compared with that of painting, seems to be chiefly attributable to such a diversity. An analogous difference, but less marked, exists between taste and smell.

Interior sensation.

There is a second class of sensations, forming the natural transition from the study of the sensations to that of the affective and intellectual functions, which all physiologists, since the time of Cabanis, and yet more, of Gall, have found it necessary to admit, to complete the study of the sensations. They are the interior sensations which relate to the satisfaction of the natural wants; and, in a pathological state, the pains produced by bodily alteration. These are still more indispensable than the first to the perfection of the organic life; and, though they procure no direct notions of the external world, they radically modify, by their intense and continuous action, the general course of intellectual operations, which are, in most animal species, entirely subordinated to them. This great department of the theory of sensations is even more obscure and unadvanced than the foregoing. The only positive notion which is fairly established in regard to it is that the nervous system is indispensable to both kinds of sensibility.

Once again we see how the extreme imperfection of doctrine here is owing to the imperfection of method; and that again, as before, to the inadequate preparation of the inquirers to whom the study belongs. It is a great thing, however, to have withdrawn the subject from the control of the metaphysicians; and some labours of contemporary physiologists authorize us to hope that the true spirit of the inquiry is at length entered into; and that the study of the sensations will be directed, as it ought to be, to develope the radical accordance between anatomical and physiological analysis.

Mode of

action of animality.

Having reviewed the two orders of animal functions, we must consider the complementary part of the theory of animality;-the ideas about the mode of action which are common to the phenomena of irritability and sensibility. It is true, these ideas belong also to intellectual and moral phenomena; but we must review them here, to complete our delineation of the chief aspects of the study of animal life.