The Full Wiki

More info on Popular Science Monthly/Volume 4/December 1873/A New Method with the Brain

Popular Science Monthly/Volume 4/December 1873/A New Method with the Brain: Wikis

Advertisements

Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

Source material

Up to date as of January 22, 2010

From Wikisource

Popular Science Monthly Volume 4 December 1873 in the year 1873
A New Method with the Brain
Scans

[ 183 ]

A NEW METHOD WITH THE BRAIN[1]

By Professor FERRIER.

ALL are agreed that it is with the brain that we feel, and think, and will; but whether there are certain parts of the brain devoted to particular manifestations, is a subject on which we have only imperfect speculations or data too insufficient for the formation of a scientific opinion. The general view is that the brain as a whole [ 184 ] subserves mental operations, and that there are no parts specially devoted to any particular functions. This has been recently expressed by so high an authority as Prof. Sequard. The idea rests chiefly on the numerous facts of disease with which we are acquainted. There are cases where extensive tracts of brain are destroyed by disease, or re- moved after a fracture, apparently with no result as regards the mind of the individual. Along with these facts we have others which are very curious, and which hardly seem to agree with this doctrine. One of these is, that when a certain part of the brain is diseased, in apha- sia, the individual is unable to express himself in words. Other curi- ous phenomena have been well described by Dr. Hughlings Jackson, viz., that certain tumors or pathological lesions in particular parts of the brain give rise, by the irritation which they keep up, to epilepti- form convulsions of the whole of one side, or of the arm, or leg, or the muscles of the face ; and, from studying the way in which these con- vulsions show themselves, he was able to localize very accurately the seat of the lesion.

The great difficulty in the study of the function of the brain has been, in the want of a proper method. When we study the function of a nerve, we make our experiments in two ways : In the first place, we irritate the nerve by scratching or by electricity, or by chemical action, and observe the effect ; and, in the second place, we cut the nerve, and observe what is lost. In regard to the brain and nervous system, the method has been almost entirely, until recently, the method of section. It has been stated by physiologists that it is impossible to excite the brain into action by any stimulus that may be applied to it, even that of an electric current ; they have, therefore, adopted the method of destroying parts of the brain. This method is liable to many fallacies. The brain is such a complex organ, that to destroy one part is necessarily to destroy many other parts, and the phenom- ena are so complex, that one cannot attribute their loss to the failure only of the parts which the physiologists have attempted to destroy.

About three years ago, two German physiologists, Fritsch and Hitzig, by passing galvanic currents through parts of the brains of dogs, obtained various movements of the limbs, such as adduction, flexion, and extension. They thus discovered an important method of research, but they did not pursue their experiments to the extent that they might have done, and perhaps did not exactly appreciate the significance of the facts at which they had arrived.

I was led to the experiments which I shall have to explain, by the effects of epilepsy and of chorea, which have been explained to depend upon irritation of parts of the brain. I endeavored to imitate the effects of disease on the lower animals, and determined to adopt the plan of stimulating the parts of the brain by electricity, after the man- ner described by Fritsch and Hitzig.

I operated on nearly a hundred animals of all classes fish, frogs, [ 185 ] A NEW METHOD WITH THE BRAIN. 185

fowls, pigeons, rats, Guinea-pigs, rabbits, cats, dogs, jackals, and mon- keys. The plan was to remove the skull, and keep the animal in a state of comparative insensibility by chloroform. So little was the operation felt, that I have known a monkey, with one side of the skull removed, awake out of the state induced by the chloroform, and proceed to catch fleas, or eat bread-and-butter. When the animal was ex- hausted, I sometimes gave it a little refreshment, which it took in the midst of the experiments.

First, as to the experiments on cats, I found that, on applying the electrode to a portion of the superior external convolution, the animal lifted its shoulder and paw (on the opposite side to that stimulated) as if about to walk forward ; stimulating other parts of the same con- volution, it brought the paw suddenly back, or put out its foot as if to grasp something, or brought forward its hind-leg as if about to walk, or held back its head as if astonished, or turned it on one side as if looking at something, according to the particular part stimulated. The actions produced by stimulating the various parts of the middle external convolution were, a drawing up of the side of the face, a back- ward movement of the whiskers, a turning of the head, and a contrac- tion of the pupil, respectively. A similar treatment of the lower ex- ternal convolution produced certain movements of the angles of the mouth ; the animal opened the mouth widely, moved its tongue, and uttered loud cries, or mewed in a lively way, sometimes starting up and lashing its tail as if in a furious rage. The stimulation of one part of this convolution caused the animal to screw up its nostrils on the same side ; and, curiously enough, it is that part which gives off a nerve to the nostril of the same side.

Results much of the same character were produced by the stimula- tion of the corresponding or homologous parts of the rat, the rabbit, and the monkey. Acting upon the anterior part of the ascending frontal convolution, the monkey was made to put forward its hand as if about to grasp. Stimulation of other portions acted upon the biceps, and produced a flexing of the forearm, or upon the zygomatic muscles. The part that appeared to be connected with the opening of the mouth and the movement of the tongue was homologous with the part af- fected in man in cases of aphasia. Stimulation of the middle temporo- sphenoidal convolution produced no results ; but the lower temporo- sphenoidal, when acted upon, caused the monkey to shut its nostrils. No result was obtained in connection with the occipital lobes.

These experiments have an important bearing upon the diagnosis in certain kinds of cerebral disease, and the exact localization of the parts affected. I was able to produce epileptic convulsions of all kinds in the animals experimented upon, as well as phenomena resembling those of chorea or St. Vitus's dance. The experiments are also impor- tant anatomically, as indicating points of great significance in reference to the homology of the brain in lower animals and in man, and like-

�� � [ 186 ] i86 THE POPULAR SCIENCE MONTHLY,

wise served to explain some curious forms of expression common to man and the lower animals. The common tendency, when any strong exertion is made with the right hand, to retract the angle of the mouth and open the mouth on the same side, had been stated by Oken, in his "Natur-ge8chichte" to be due to the homology between the upper limbs and the upper jaw ; the true explanation being that the movements of the fist and of the mouth are in such close relation to each other that, when one is made to act powerfully, the impression diffuses itself to the neighboring part of the brain, and the two act together.

The experiments have likewise a physiological significance. There is reason to believe that, when the different parts of the brain are stimu- lated, ideas are excited in the animals experimented upon, but it is difficult to say what the ideas are. There is, no doubt, a close relation between certain muscular movements and certain ideas, which may prove capable of explanation. This is supported by the phenomena of epileptic insanity. The most important guide on the psychological aspect of the question is the disease known as aphasia. The part of the brain which is the seat of the memory of words is that which gov- erns the movements of the mouth and the tongue. In aphasia, the disease is generally on the left side of the brain, in the posterior part of the inferior frontal convolution, and it is generally associated with paralysis of the right hand, and the reason might be supposed to be that the part of the brain affected is nearly related to the part govern- ing the movements of the right hand.

It is essential to remember that the movements of the mouth are governed bi-laterally from each hemisphere. The brain is symmetrical, and 1 hold it to be a mistake to suppose that the faculty of speech is localized on the left side of the brain. The reason why an individual loses his speech when the left side of the brain is diseased is simply this : Most persons are right-handed, and therefore left-brained, the left side of the brain governing the right side of the body. Men naturally seize a thing with the right hand, they naturally therefore use rather the left side of the brain than the right, and when there is disease, there the individual feels like one who has suddenly lost the use of his right arm.

I may, finally, briefly allude to the results of stimulating the dif- ferent ganglia. Stimulation of the corpora striata causes the limbs to be flexed ; the optic thalami produces no result : the corpora quadri- gemina produce, when the anterior tubercles are acted upon, an intense dilatation of the pupil, and a tendency to draw back the head and ex- tend the limbs as in opisthotonos ; while the stimulation of the pos- terior tubercles leads to the production of all kinds of noises. By stimulating the cerebellum, various movements of the eyeballs are produced. Nature,

�� �

[ 187 ]

MARS, BY THE LATEST OBSERVATIONS

FROM THE FRENCH OF CAMILLE FLAMMARION.

IN order successfully to observe Mars, two conditions are requisite: First, the earth's atmosphere must be clear at the point of observation; and, second, the atmosphere of Mars must be also free from clouds—for that planet, like the earth itself, is surrounded by an aerial atmosphere which from time to time is obscured by clouds just like our own. These clouds, as they spread themselves out over the continents and seas, form a white veil which either entirely or partially conceals from us the face of the planet. Hence the observation of Mars is not so easy a matter as it might at first appear. Then, too, the purest and most transparent terrestrial atmosphere is commonly traversed by rivers of air, some warm, some cold, which flow in different directions above our heads, so that it is almost impossible to sketch a planet like Mars, the image seen in the telescope being ever undulating, tremulous, and indistinct. I believe that, if we were to reckon up all the hours during which a perfect observation could be had of Mars, albeit his period of opposition occurs every two years, and although telescopes were invented more than two and a half centuries ago, the sum would not amount to more than one week of constant observation.

 And yet, in spite of these unfavorable conditions, the Planet of War is the best known of them all. The moon alone, owing to its nearness to us, and the absence of atmosphere and clouds, has attracted more particular and assiduous study; and the geography (selenography[2] rather) of that satellite is now satisfactorily determined. That hemisphere of the moon which faces us is better known than the earth itself; its vast desert plains have been surveyed to within a few acres; its mountains and craters have been measured to within a few yards; while on the earth's surface there are 30,000,000 square kilometres (sixty times the extent of France), upon which the foot of man has never trod, which the eye of man has never seen. But, after the moon, Mars is the best known to us of all the heavenly bodies. No other planet can compare with him. Jupiter, which is the largest, and Saturn the fullest of curious interest, are both far more important than Mars, and more easily observed in their ensemble, owing to their size; but they are enveloped with an atmosphere which is always laden with clouds, and hence we never see their face. Uranus and Neptune are only bright points. Mercury is almost always eclipsed, like a courtier, by the rays of the sun. Venus alone may compare with Mars; she is as large as the earth, and consequently has twice the [ 188 ] 188 TEE POPULAR SCIENCE MONTHLY.

diameter of Mars ; besides, she is nearer to us, her least distance being about 30,000,000 miles. But, one objection is, that Venus revolves be- tween the sun and us, so that, when she is nearest, her illuminated hemisphere is toward the sun, and we see only her dark hemisphere edged by a slight luminous crescent, or, rather, we do not see it at all. Hence it is that the surface of Venus is harder to observe than that of Mars, and hence, too, it is that Mars has the preeminence, and that in the sun's whole family he is the one with which we shall first gain acquaintance.

Fig. 1.

���Aspect of Mars, with its Cap op Polar Snow.

The geography of Mars has been studied and mapped out. What principally strikes one on studying this planet is that its poles, like those of the earth, are marked by two white zones, two caps of snow, one of which is shown in the cut. Sometimes both of these poles are so bright that they seem to extend beyond the true bounds of the planet. This is owing to that effect of irradiation which makes a white circle appear to us larger than a black circle of the same di- mensions. These regions of ice vary in extent, according to the sea- son of the year ; they grow in thickness and superficial extent around both poles in the winter, melting again and retreating in the summer. They have a larger extension than our glacial regions, for sometimes they descend as far as Martial latitude 45, which corresponds with the terrestrial latitude of France.

This first view of Mars shows an analogy with our own planet, in the distribution of climates into frigid, temperate, and torrid zones. The study of its topography will, on the other hand, show a very char- acteristic dissimilarity between the configuration of Mars and that of the earth. On our planet the seas have greater extent than the con-

�� � [ 189 ] MARS, BY THE LATEST OBSERVATIONS. 189

tinents. Three-fourths of the surface of our globe is covered with water. The terra firma is divided chiefly into three great islands or continents, one extending from east to west, and constituting Europe and Asia ; the second, situated to the south of Europe, in shape like a V with rounded angles, is Africa ; the third is on the opposite side of the earth, and lies north and south, forming two V's, one above the other. If to these we add the minor continent of Australia, lying to the south of Asia, we have a general idea of the configuration of our globe.

It is different with the surface of Mars, where there is more land than sea, and where the continents, instead of being islands emerg- ing from the liquid element, seem rather to make the oceans mere inland seas genuine mediterraneans. In Mars there is neither an Atlantic nor a Pacific, and the journey round it might be made dry- shod. Its seas are mediterraneans, with gulfs of various shapes, ex- tending hither and thither in great numbers into the terra firma, after the manner of our Red Sea.

Fig. 2.

���Chart of the Surface of Mabs, showing the Distribution of Land and Water.

��The second character, which also would make Mars recognizable at a distance, is that the seas lie in the southern hemisphere mostly, oc- cupying but little space in the northern, and that these northern and southern seas are joined together by a thread of water. On the entire surface of Mars there are three such threads of water extending from the south to the north, but, as they are so wide apart, it is but rarely

�� � [ 190 ] 190 THE POPULAR SCIENCE MONTHLY.

that more than one of them can be seen at a time. The seas and the straits which connect them constitute a very distinctive character of Mars, and they are generally perceived whenever the telescope is di- rected upon that planet.

The continents of Mars are tinged of an ochre-red color, and its seas have for us the appearance of blotches of grayish green intensi- fied by the contrast with the color of the continents. The colpr of the water on Mars is therefore that of terrestrial water. But why is the land there red? It was at one time supposed that this tinge must be owing to the Martial atmosphere. It does not follow that, because our atmosphere is blue, the atmosphere of the other planets must have the same color. Hence it was permissible to suppose that the atmos- phere of Mars was red. In that case the poets of that world would sing the praises of that ardent hue, instead of the tender blue of our skies. In place of diamonds blazing in an azure vault, the stars would be for them golden fires flaming in a field of scarlet ; the white clouds suspended in this red sky, and the splendors of sunset, would produce effects not less admirable than those which we behold from our own globe.

But the case is otherwise. The coloration of Mars is not owing to its atmosphere ; for, although the latter is spread out over the entire planet, neither its seas nor its polar snows assume the red tinge ; and Arago, by showing that the rim of the planet's disk is of a less deep tinge than the centre, proved that the color is not due to the atmos- phere. If it were, then the rays reflected from the margin to us would be of a deeper red than those reflected from the centre, as having to pass through a greater height of atmosphere. May we at- tribute to the color of the herbage and plants, which no doubt clothe the plains of Mars, the characteristic hue of that planet, which is noticeable by the naked eye, and which led the ancients to personify it as a warrior ? Are the meadows, the forests, and the fields, on Mars, all red? An observer, looking out from the moon, or from Venus, upon our own planet, would see our continents deeply tinged with green. But, in the fall, he would find this tint disappearing at the latitudes where the trees lose their leaves. He would see the fields varying in their hues, and then would come winter, when they would be covered with snow for months. On Mars the red coloration is constant ; it is observed at all latitudes, and in winter no less than in summer. It varies only in proportion to the clearness of the atmos- pheres of Mars and the earth. Still this does not preclude the suppo- sition that the Martial vegetation has its share in producing the red hue of the planet, though it be principally due to the color of the soil. The land cannot be all over bare of vegetation, like the sands of Sa- hara. It is very probably covered with a vegetation of some kind, and, as the only color we perceive on Mars's terra firma is red, we con- clude that Martial vegetation is of that color.

�� � [ 191 ] MAES, BY THE LATEST OBSERVATION'S. 191

"We speak of plants on Mars, of the snows at its poles, of its seas, atmosphere, and clouds, as though we had seen them. Are we justi- fied in tracing all these analogies ? In fact, we see only blotches of red, green, and white, upon the little disk of the planet ; but, is the red terra firma ; the green, water ; or the white, snow ? Tes, we are now justified in saying that they are. For two centuries astronomers were in error with regard to spots on the moon, which were taken for seas, whereas they are motionless deserts, desolate regions where no breeze ever stirs. But it is otherwise as regards the spots on Mars.

The unvarying aspect of the moon never exhibits the slightest cloud upon its surface, nor do the occultations of stars by its disk re- veal even the slightest traces of an atmosphere. Contrariwise, the aspect of Mars is ever varying. White spots move about over its disk, very often modifying its apparent configuration. These spots can be nothing else but clouds. The white spots at its poles increase or di- minish with the seasons, exactly like the circumpolar ice of earth, which, for an observer on Yenus, would have the same aspect and the same variations as the polar spots of Mars have for us. Hence we conclude that these Martial white polar spots are masses of frozen water. Each hemisphere of Mars is harder to observe during its win- ter than during its summer, being often covered with clouds over its greater part. This would be precisely the aspect of the earth if ob- served from Yenus. But what causes these clouds over Mars ? Plainly nothing else but the evaporation of water. As for the ice, that is the same water frozen. But is the water there the same as here ? Down to a few years ago, this question remained unanswered, but now it ad- mits of a reply, thanks to the spectroscope, and the observations espe- cially of Mr. Huggins.

The planets reflect the light they receive from the sun ; on examin- ing their spectra, we find the solar spectrum as though it had been re- flected from a mirror. If we direct the spectroscope on Mars, we get, first of all, an image perfectly identical with that produced by the central star of our system. But, by the employment of more exact methods, Mr. Huggins found, during the last opposition of the planet, that the spectrum of Mars is crossed, in its orange portion, by a group of black lines coincident with the lines which appear in the solar spec- trum at sunset when the sun's light passes through the denser strata of our atmosphere. Now, are these tell-tale rays produced by our at- mosphere ? To decide this question, the spectroscope was turned on the moon, which was at the time nearer the horizon than Mars. If the lines in question were produced by our atmosphere, they must have appeared in the lunar as well as in the Martial spectrum, and with greater intensity in the former. Yet they were not to be seen at all in the lunar spectrum ; and hence it is plain that they are owing to the atmosphere of Mars.

The atmosphere of that planet, therefore, adds these special char-

�� � [ 192 ] i 9 2 THE POPULAR SCIENCE MONTHLY.

acters to those of the solar spectrum, and this proves that the atmos- phere of Mars is analogous to that of earth. But what is that atmos- pheric matter which produces these significant lines ? From an exami- nation of their positions, we find that they are not owing to the presence of oxygen, nitrogen, or carbonic acid, but to watery vapor. There- fore, there is water-vapor in the atmosphere of Mars, as in that of the earth. The green spots on its globe are seas expanses of water re- sembling our seas. The clouds are made up of minute vesicles of water, like our own mists ; and the snows consist of water solidified by cold. Furthermore, this water, as revealed by the spectroscope, being of the same chemical composition as terrestrial waters, we know that Mars possesses oxygen and hydrogen.

These important data enable us to form an idea of Martial me- teorology, and to recognize therein a reproduction of the meteorologi- cal phenomena of our own planet. On Mars, as on earth, the sun is the supreme agent of motion and of life. Heat vaporizes the water of the seas, causing it to ascend into the atmosphere. This vapor as- sumes visible shape by the same processes which produce clouds here, i. e., by differences of temperature and of saturation. Winds arise in virtue of these same differences of temperature. We can observe the clouds on Mars as they are swept along by air-currents over the seas and continents, and several observers have, so to speak, photographed these meteoric variations.

If we are as yet unable precisely to see the rain falling on the plains of Mars, we can at least tell when it is falling, for we can see the clouds dispersing and gathering again. Thus there is on Mars, just as on 'earth, an atmospheric circulation, and the drop of water which the sun takes from the sea returns thither after it has fallen from the cloud which concealed it. And, although we must sternly resist any tendency to fashion imaginary worlds after the pattern of our own, still Mars presents to us, as in a mirror, such an organic like- ness to earth, that it is hard for us not to carry our description a little further.

Thus, then, we behold, in space, millions of miles away, a planet very much like our own, and where all the elements of life exist, as they do here water, air, heat, light, winds, clouds, rain, streams, val- leys, mountains. To complete the resemblance, the seasons there are very much the same as here, the axis of rotation of Mars having an inclination of 27, while that of the earth is 23. The Martial day is forty minutes longer than the terrestrial.

In the face of all these facts, can we be content with the conclu- sions we have so far reached without going further, and considering ulterior consequences ? If the same physico-chemical conditions are present on Mars as on earth, why should they not produce the same effects there as here ? On earth the smallest drop of water is peopled with myriads of animalcules, and earth and sea are filled with count-

�� � [ 193 ] less species of animals and plants; and it is not easy to conceive how, under similar conditions, another planet should be simply a vast and useless desert.—La Nature.

Ruler side.gifRuler center.gifRuler side.gif
  1. A paper read before the Biological Section of the British Association.
  2. Serene, the moon.
Advertisements

Advertisements






Got something to say? Make a comment.
Your name
Your email address
Message