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philosopher, who is not a physiologist, labours under a disadvantage. in his investigations, which scarcely any acuteness can compensate ; while a knowledge of this science will most essentially aid the highest powers of analysis and classification with which he may be endowed.
A thorough acquaintance with this science was then shown to be indispensable to those who are to engage in the practice of medicine; for if the philosopher cannot understand the laws of the mind without having studied the physiology of the body, how is it possible that those whose office it is to rectify the disordered functions of both, can proceed a single step in the performance of their duty without any precise knowledge of either. What! it was asked, is a physician ignorant of physiology at the bed-side of the sick? He is to discover some corporeal or mental disease; he is to ascertain its seat, its nature, its degree; but the only indication of disease is disorder of function. The affected organ cannot be seen: what is going on within it, is not an object of sense: it can be inferred only from the observation of the derangement which takes place in its healthy action: but how can he comprehend its disordered, if he know not its healthy function. He who without this knowledge presumes to take a single step in the treatment of any serious disease, can be saved from shame and remorse only by a moral insensibility, which, though it may be an appropriate punishment for his conduct, unfortunately can be no security against the mischief of which it is the cause.
It was then observed, that a knowledge of human nature, acquired by the study of the physiology of the human body and of the human mind, would be pre-eminently real, exact, comprehensive, and practical, and would therefore be of the highest possible value to those who have to instruct, to govern, or to influence in any way the opinions and conduct of men. It would give to the philanthropist, the legislator, and the statesman, more real power than mines of gold, than a thousand prisons, than millions of armed men. To attempt the improvement of the physical, the mental, the moral, and the social condition of man; to endeavour to call forth his most powerful and noble energies, and to direct them to the public good, without a knowledge of his mental and moral constitution, is not only a vain, but a perilous, and as experience too uniformly teaches, a most precarious undertaking.
Yet the ignorance on this subject of those in whose hands the destinies of mankind are placed, is profound and almost universal. No provision whatever is made for the communication of this kind of knowledge. The consequence is, that some of the most severe and intolerable of the evils that afflict mankind arise from the very efforts of benevolence-from the very measures of legislation, while both labour, sometimes with the utmost sincerity, to promote the prosperity and to counteract the misery of the social state. In the physical and the mental weakness of man without doubt will evermore spring up, even when these efforts are the most enlightened and the best directed, abundant sources of unhappiness; but there can be no question that that unhappiness has been, and continues to be, increased a thousand fold by the wonderful ignorance that prevails of man's real, that is, of his physical and mental constitution. In the science which would remove this ignorance, and supply its place with the most beneficial knowledge, there is nothing singularly difficult-nothing peculiarly
technical-nothing which might not be explained in the common language of mankind, and communicated with the utmost ease as a part of general education in the higher schools, and in the later courses of instruction. The philosopher, who has studied man by making himself acquainted with the structure of his body and mind, and with the laws to which both are obedient, has long seen and lamented the consequences of this ignorance in the misdirected energies, the disappointed expectations, and the counteracted efforts of the philanthropist and patriot: but he who shall succeed in so directing the public attention to it as to lead to its removal, will deserve, and will receive, the gratitude of his country as one of its benefactors.
After explaining certain terms, which are often employed in physiology, and to which a precise and correct notion is not always attached, such as phenomena, their quality, order and succession, analysis, cause, effect, power, law, hypothesis, theory, the Lecturer proceeded to discuss the interesting and important subject of organi
Life, it was stated, depends on certain conditions: these conditions consist in certain arrangements of material substances: such arrangements of material substances constitute organization: it follows that organization is the essential condition of life. If without attending to the controversies which have been agitated on this subject, we carefully study phenomena, and mark their order, the first thing we observe in a living being is a peculiar arrangement of particular textures; that is, a specific organization: the second thing we discover is, that the textures thus arranged exercise peculiar actions; that is, this peculiar organization performs a specific function. A determinate organization constitutes what is called an organ: the action of every organ constitutes what is denominated its function. Without the organ there is no function; for the plain reason, that without the agent that acts there can be no action. In the order of phenomena, therefore, organization, which is the primary condition of life, must necessarily precede the actions of that organization in which the functions of life consist. Organization is the antecedent; function is the sequent.
If it be asked what is the origin of the organization to which function is related as the sequent; it is replied, a pre-existing organization, constituted similarly to itself, and exercising functions in all respects the same as those it communicates. Organization is not self-existent : but it is invariably pre-existent. Matter neither organizes itself, nor is organized, as far as is yet ascertained, by any cause but one-a preexisting organization. To inquire into the primitive formation of this pre-existing organization, is to inquire into the first origin of animal existence; an inquiry which, as there are no means by which it can possibly be answered, is not a legitimate object of human investigation. To confound with this inquiry that of the order of the phenomena of life, we should have deemed impossible, had not experience taught us how constantly the error is committed; and did we not know, that to this very identification of subjects so widely and so obviously different, are to be traced the vague fears sometimes entertained respecting the tendency of these investigations, and the real credulity discernible
through the boasted scepticism which pretends that every thing relating to life can be explained by the ordinary laws and affinities of matter. The first origin of life-the production in every particular species of living beings of a germ on which the perpetuation of its own peculiar mode of life depends, is indeed most wonderful-most mysterious; but no more wonderful or mysterious than the constitution of any other part of nature. It is only one of a general class of facts. For if any thing analogous to that species of knowledge of which philosophers have endeavoured to conceive, and of which they have spoken under the name of the intimate, or the essential constitution of things, we are entirely destitute, and our ignorance must always remain just as profound as it is. Human knowledge must always be limited to an acquaintance with the number, the quality of the order of phenomena, and their mutual influence.
It has been stated that every particular organ is the seat of some special function. A function consists of certain phenomena, which have a peculiar relation to each other, and which concur in the production of a definite object. In general these phenomena compose a series; their succession in the series is always fixed and invariable. The phenomena which occur in respiration, for example, such as the motion of the muscles which raise the ribs and depress the œsophagusthe increase of cavity in the cells of the lungs-the ingress of atmospherical air into that cavity-the change produced in the qualities of the blood during its passage through the lungs, and so on, compose a train of events, the whole of which when taken together constitute the process or the function termed respiration. In this series, the phenomena invariably follow each other in a certain order: all concur in the production of a definite object. The same is true of every function of every living being.
The consideration of function leads directly to the observation of the characters by which the two great classes of living beings, vegetable and animal, are distinguished from each other. These characters consist of certain faculties which are exercised by the one, but of which the other is destitute.
The vegetable is the most simple of organized bodies. It possesses only those faculties which are indispensable to life, and which are therefore common to all living beings. Strictly speaking, this consists of one faculty only, namely, that of nutrition. Every living being must possess the power of assimilating foreign materials into its own substance; but because it is conceivable that a living being might continue to exist for an indefinite period without exercising any other function, therefore this must be considered as the only one which in strictness is absolutely indispensable to life. Since, however, it is a law of the animal economy, that life springs from life only, a class of beings unendowed with the power of communicating to their descendants a nature similar to their own, must perish with the primitive race. The faculty of reproduction is therefore invariably added to that of nutrition. The plant absorbs nourishment and developes a germ, the evolution of which constitutes a being which possesses a similar organization, and which performs a similar function. To these two are limited all the functions exercised by this extensive class of organized bodies.
On the other hand, animals possess at least two additional faculties; namely, sensation and voluntary motion. All animals are capable of
some degree of sensation, and all (with few exceptious) are able to move from place to place according to the impulse of sensation. The functions of animals consist therefore of two great classes. First, of those which they possess in common with vegetables, and which are therefore termed vegetative; on which, because they are absolutely essential to the maintenance of life in the individual, and to the perpetuation of it in the species, are sometimes denominated vital: these are mutation and generation. The second consists of those which are peculiar to animals, which, because they belong exclusively to this division of living beings, are called animal functions: those are sensation and voluntary motion.
The proof that those characters are real, invariable, and universal, (for such characters alone can mark with philosophical accuracy the distinction between these two divisions of living beings,) is derived chiefly from observing the difference in the kind of motion which is made by the vegetable and the animal. Mere motion is not a distinctive property of animal life: for though the vegetable is in general confined to one spot, and is incapable of any thing that bears the least resemblance to spontaneous motion, yet there are several apparent and very striking exceptions to this rule. The sensitive plant shrinks from the touch, and instantly folds up its leaves. The flowers of innumerable plants alter their direction according to the circumstances in which they are placed. The roots of all plants have the power of discovering and of proceeding towards that situation which is the best adapted to afford them nourishment. A plane-tree which grew on the top of a wall among the ruins of New Abbey, and which became exceedingly straitened for nourishment in that situation, was observed to direct its roots down the side of the wall, till they reached the ground, which was ten feet below. If the root of a tree meets with a ditch in its progress, by which it is in danger of being laid open to the air, it alters its course, plunges into the ground, surrounds the ditch, rises on the opposite side to its wonted distance from the surface, and then proceeds in its original direction.
If a wet sponge be placed near a root exposed to the air, the root will direct its course to the sponge: if the place of the sponge be changed, the root will vary its direction. If the branch of a tree be twisted so as to invert its leaves, and it be fixed in that position, only still left in some degree loose, it will untwist itself gradually, till the leaves are restored to their natural position. Curious and interesting as these and other examples of the movements of plants are, they afford no real indication that such movements are spontaneous; that they proceed from volition excited by sensation: because there is no evidence that any plant is capable of sensation. Motion itself cannot be considered as any proof of the possession of this faculty. Even unorganized matter, (an electrified silk thread, for example,) is capable of a greater variety of motion than any species of sensitive plant. If a bit of silk thread be dropt in an electrified metal plate, it will erect itself, spread out its small fibres like arms, and if not detained, will fly off. If a candle be made to approach it, it will clasp close to the plate, as if afraid of it ;yet when we observe the whole of the phenomena, we perceive that it affords no indication that it possesses sensation. A human being knows from consciousness that he himself possesses sensation: that any other human being, that any other animal possesses it, is to him a matter of
inference only. By what means does he arrive at the conclusion? by observing, that his fellow beings, and that other animals, act in all similar circumstances in a manner similar to himself. From this fact he deduces the inference, that in similar circumstances other animals feel similarly.
Now vegetables afford no indication whatever that they feel like animals, because when placed in similar circumstances they do not act similarly. All animals whose possession of sensation is certain, not only move when danger approaches, but the motion is indicative of a desire and an attempt to escape from the danger. But the electrified thread, though it fly from the candle to cling to the metal, allows itself to be burnt there without offering to stir. The sensitive plant, though it contracts on being touched, permits itself to be cut in pieces without making the slightest motion indicative of an effort to escape. On the contrary, the lowest animal, the oyster or the muscle, not only contracts when touched, but its contraction places the animal in comparative security; and the animal obviously makes the kind of motion it does, in order to avail itself of the means with which nature has furnished it to avert impending danger. Though, therefore, motion be common to the thread, to the plant, and to the animal, yet from circumstances connected with the motion, we conclude that in the latter it results from volition, while in the former it is unattended with consciousness.
Though this reasoning would be sufficient to satisfy the naturalist and the philosopher, yet there is one other proof which, though negative, is obvious to every one, and is quite decisive. Man, in common with all other animals, possesses both animal and vegetable life. By the observation of what passes within ourselves, we know that there is no connection whatever between mere vegetation and sensation. We are conscious that we exist: we are not conscious of the operation of the vegetative functions by which we exist. Of all the processes by which the aliment is converted into blood, and the blood into the proper substance of the body, complicated as those processes are in an animal so high in the scale as man, as long as they continue healthy, we are wholly insensible. Why then should we imagine that these functions are attended with consciousness in the vegetable in which the processes themselves are so much more simple. If a wound be made in any part of the body, attended with the loss of substance, and the loss be repaired, new fibres arrange themselves, not only as if they were animated and intelligent, but the degree of wisdom with which they are disposed is absolutely perfect; yet all this is effected, not only without our having the least knowledge of the mode in which it is done, but even without our being sensible that it is done at all. We have therefore in ourselves a demonstration that vegetable life exists and acts without consciousness.
Notwithstanding, therefore, the labour which ingenious men have taken to perplex this subject, the faculties of sensation and voluntary motion do afford characters sufficiently real, invariable, and universal, to constitute a broad line of demarcation between these two great divisions of living beings.
We find that we have arrived at the end of our time and space without establishing ourselves much deeper than in the vestibule of these lectures. In our subsequent notices, having laid the foundation, we shall take a more rapid sketch of Dr. Smith's views.