Physiography

“ Thus the two sciences of astronomy and physiology discovered and developed the methods of investigating mental times; the further development was the task of psychology.
Another source of the new psychology is to be found in the physiological study of the sense organs. The most obvious method for determining the functions of the nerves and end organs of the skin—the nose, the ear, or the eye—is to ask the living subject what he feels when various stimuli are applied. In this way there has arisen a large body, of knowledge concerning the sensory functions of the nervous system. ”

“ Turning to the physical side of physiology, it is unnecessary here to say more about the means employed for studying the properties of muscle and nerve than that many of the phenomena occur with such extreme rapidity that they can only be perceived by the photographic plate. In the study of the large organs, the physiologist finds a fascinating employment in devising models in which, so far as possible, all the physical conditions are reproduced, and this not only for the benefit of his pupils, but to help himself in perceiving their meaning. ”

“ Anatomy shows us that animals and plants are wonderfully constructed. But after we understand their architecture and even their minute structure, the questions remain: What are all the organs and tissues for, and what takes place within the parts that are actually alive? Physiology attempts to answer questions of this nature. It therefore stands in contrast with anatomy and is supplementary to it. The activities of the body are varied and depend on life for their manifestation — they may be called vital activities. Physiology embraces a study of them all. ”

“ Indeed, it may truly be said that, alike in anatomy and in physiology, the whole present knowledge of the brain, the spinal cord and the nerves, is in great measure due to the use of experiments on animals. And this knowledge is daily applied to the diagnosis and treatment of diseases and injuries of the central nervous system. “In the case of operations on the brain, you have to form your opinion as to what is going on entirely from your knowledge of the physiology of the brain, and that we owe, of course, in the greatest measure to the discoveries of Hitzig and Fritsch and Ferrier.” ”

“ The fibres of nervous matter are universally present in the organization, uniting the physical and spiritual elements of man's being. Even the minutest nerve-rootlets convey impressions to the dome of thought and influence the intellectual faculties. We recognize muscular force, the strength of the body, molecular force, molecules in motion, as heat, light, chemical force, electricity, and nervous force, a certain influence which reacts between the animal functions and the cerebrum, thus connecting the conditions of the body with those of the mind. ”

“ In recent times physiology has indeed made great, and to many startling, advances in the direction of connecting mental phenomena with brain-changes. Physiologists have established the correlation of physical and chemical with vital forces, and probably of vital with mental forces. They have proved in every act of perception the existence of a vibratory thrill passing along the nerve-cord from sense-organ to brain; and in every act of volition a similar vibratory thrill from brain to muscle ”

“ In the History of Physiology, I have already related the progress of the researches by which the organs employed in voluntary motion became known to anatomists. It was ascertained to the satisfaction of all physiologists, that the immediate agents in such motion are the muscles; that the muscles are in some way contracted, when the nerves convey to them the agency of the will; and that thus the limbs are moved. It was ascertained, also, that the nerves convey sensations from the organs of sense inwards, so as to make these sensations the object of the animal’s consciousness. ”

“ Applying this remark to physiology, we see that the nerves and brain as physical objects are not truly data; they are to be replaced, in the ideal structure of science, by the sensations through which the physiologist is said to perceive them. The passage from these sensations to nerves and brain as physical objects belongs really to the initial stage in the theory of physics, and ought to be placed in the reasoned part, not in the part supposed to be observed. To say we see the nerves is like saying we hear the nightingale ”

“ THE first task of physiology was to localize the functions of life in the various organs of the body which serve as their instruments. Thus digestion was assigned to the stomach, circulation to the heart, respiration to the lungs; thus, too, the seat of intelligence and thought was placed in the brain. Still, with regard to the latter organ, a reservation was thought proper, excluding the idea that the metaphysical expression of the intellectual and moral powers was the manifestation, simply and merely, of the cerebral function. ”

“ The transfer of this condition of the nerve-fiber to the central parts of the nervous system, especially to the brain. These are the mechanical antecedents for sensation. They are susceptible of physical treatment. They may, and often do, operate without any sensation arising; more than this, they may operate so as to produce a reflex activity, causing violent motions, still without the faintest appearance of sensation. It is plain, then, that to know anything about sensation we must pass from physiology to personal experience. ”

“ The physiology of a sense, consists in an external organ,—as the eye or ear, its nerves of sensation which spread through the brain, and, the nervous fluid. To each of the senses there belongs a distinct cerebral organ, which, if deducted, leaves nothing to constitute the physiology, but the exter [Pg 18] nal organ, the nerves, and nervous fluid; such may be considered the physiology of all the senses, so far as the exciting mental perception is concerned. ”

“ From this, we advance to the nerve centre,—the brain,—to which the nerves of sensibility run up, and from which the nerves of motion come forth. Here also there is identity in the nature of the organ, while there is variety in its size, with more or less complicated plans of arrangement, according to the extent of the nerve system of which it is the central organ. Still keeping to the human body for illustration, we may find in the most complex organism known to us illustration of what holds good in the main so far as essential structure is concerned. ”

“ We must suppose, in short, that physical processes constitute a locked system, every subsequent state of which is fully accounted for by the immediately preceding state; that the nervous system is a highly complex mechanism for adapting the movements of an animal to environing conditions in a manner useful to the animal; and that consciousness is a parallel manifestation, concomitant to certain processes in the highest nerve-centres. ”

“ As we approach man, in the scale of beings, we find that the organs multiply, and the functions become more complete. The function of motion, the instruments of which—the muscles and bones—have been considered in former chapters, and all the other animal functions of man, depend upon the set of organs known as the nervous system.
4. The nervous tissues, of what composed? When examined by the aid of the microscope? The white substance? The gray substance?
4. The Nervous System.—The intimate structure of this system differs from any tissue which we have before examined. ”

“ In the fifth place, modern physiology investigates the relation between physical and psychical phenomena, on the assumption that molecular changes in definite portions of nervous matter stand in the relation of necessary antecedents to definite mental states and operations. ”

“ Let any man, who has but touched the study of physiology, consider what is involved in even the most superficial observation of the simplest facts of the nervous system: for instance, the ordinary nerve-muscle preparation that is taught to every medical student, or the microscopic structure of the spinal cord, or the Wallerian method. ”

“ On the contrary, they include changes and movements in all of the so-called involuntary muscles, and in every kind of bodily structure. They include changes and movements in every part of the physical organism, from changes in the action of heart, lungs, stomach, liver and other viscera, to changes in the secretions of glands and in the caliber of the tiniest blood-vessels. A few instances such as are familiar to the introspective experience of everyone will illustrate the scope of the mind's control over the body. ”

“ The physiologist of the present day is too little of a comparative anatomist, and far too closely enveloped in the absurd jargon of the anthropotomist, ever to hope to reveal any great truth for science, and dispel the mists which still hang over the phenomena of the nervous system. ”

“ It is the man, and not the brain, that thinks: it is the organism as a whole, and not one organ, that feels and acts.
31. Consciousness, or Sensation, is a complex product not to be recognized in any one of its factors. Cerebral processes and spinal processes are the elements we analytically separate, as muscular contractions are the elements of limb-movements. The synthetic unity of these elements is a reflex; this we analytically decompose into a sensation and a movement; and then we speak of sensation as the reaction of the sensory organ, the movement as the reaction of the muscular organ. ”

“ This is because the nervous changes intervening between the reception of the stimulus and the reaction can only be rendered accessible to observation by devices which postulate for their invention an extremely advanced condition of physical science in general and of Physiology in particular. There is no direct method of translating the actual processes which we experience into an unambiguous physiological symbolism, or, vice versâ, of testing a physiological hypothesis by retranslating it into facts of direct living experience. ”

“ Everyone pays unconscious homage to the study of physiognomy when, scanning the features of a stranger, he draws conclusions concerning his intelligence, disposition, and character. Without discussing how much physiognomy is really worth, there can be no doubt that it is a mistake to place it in the same category as phrenology, since the latter lacks that sound basis of physiology which no one can deny to the former. ”

“ That understanding, when it is complete, will have been gained step by step through experiments on living animals, one of the first of which was Claude Bernard's research on vaso-motor nerves. [2]
There still remains the question, What good does physiology bring to mankind? Of the value of physiology as a not insignificant segment of the circle of universal knowledge, nothing need be said; where saying aught is necessary, it would be useless. Nor need much be said concerning the practical value of physiology as a basis for the conduct of life. ”

“ Everyone knows the doctor, and everyone knows that physiology deals with the ‘functions of different organs of the body’; but the public rarely meet the physiologist, except in the fanciful caricatures of his enemies, which though frequently personal are rarely accurate. ”

“ That the powers by which the nerves are the instruments of sensation, and the muscles of motion, are vital endowments, incapable of being expressed or explained by any comparison with mechanical, chemical, and electrical forces, is the result which we should 224 expect to find, judging from the whole analogy of science; and which thus is confirmed by the history of physiology up to the present time. We naturally, then, turn to inquire whether such peculiar vital powers have been brought into view with any distinctness and clearness. ”

“ Advance in the scale is connected with greater complexity in the organism. As we ascend, separate organs appear, fulfilling distinct functions, and controlled by means of a nerve system whose ramifications are according to the intricacy of the organism. The appearance of such a nerve system implies sensibility and motor activity, provision for an experience more or less varied, and movement in some measure according with it, or adapted to it. ”

“ If others are stimulated, the result will be the production of the state of consciousness called pain. Now, if I trace these last nerve-filaments, I find them to be ultimately connected with part of the substance of the brain, just as the others turn out to be connected with muscular substance. If the production of motion in the one case is properly said to be the function of the muscular substance, why is the production of a state of consciousness in the other case not to be called a function of the cerebral substance? ”

“ Such speculations as I have quoted respecting the nervous fluid, proceeding from some of the greatest philosophers who ever lived, prove only that hitherto the endeavor to comprehend the mystery of perception and will, of life and thought, have been fruitless and vain. Many anatomical truths have been discovered, but, so far as our survey has yet gone, no genuine physiological principle. All the trains of physiological research which we have followed have begun in exact examination of organization and function, and have ended in wide conjectures and arbitrary hypotheses. ”

“ It is plain that we cannot understand the physiology of our bodies without a knowledge of their anatomy. An engineer could not understand the working of his engine unless well acquainted with all its parts, and the manner in which they were fitted together. So, if we are to understand the principles of elementary physiology, we must master the main anatomical facts concerning the organs of the body before considering their special functions. ”