This story of pathology influencing racial qualities is not new in the history of the world. It is not improbable that even certain periods of decadence in Egyptian history which have ordinarily been attributed to the so-called running out of particular ruling races or families, or to the degeneration of the people consequent upon luxury, were really the result of the spread of the hook-worm disease through certain portions of Egypt. Dr. Sandwith, who has studied the disease very carefully in Egypt, is sure that it has existed there for at least four thousand years, and that the descriptions of certain affections which occurred in Egypt in historic times were really due to the same cause as now is known to produce the so-called Egyptian chlorosis, the name that was used for hook-worm disease in Egypt.
Workers in soil, and in mines and in tunnels, are especially likely to be affected by it, and whenever it is neglected it spreads rather widely, as is seen in the mines of Germany and Hungary at the present time. As the cause was unrecognized in the olden time, it is possible that periods of supposed la.s.situde among the people were really due to infection by this parasite.
_Malaria and Degeneration_.--In recent years it has come to be generally recognized that the decadence of Greece, for instance, was not due to moral causes so much, perhaps, as to physical reasons.
During the cla.s.sic periods in Greece there are no traces of malaria.
After the invasion of Sicily, the expedition against Syracuse and other attempts on the part of the cities of Greece to spread their dominion, malaria seems to have been introduced among her people, and as the _anopheles_ mosquito was already there, the malaria spread widely, and in the course of a century affected so many of the people that their energy and ambition and initiative were to a great extent destroyed. {108} It is well known that these effects often occur as a consequence of malaria, and as generation after generation is affected by the disease, are emphasized more and more. The relaxing effect of tropical climates, of which we have heard so much, and which is supposed after a time to bring about the inevitable production of a race eminently lazy and careless of the future, is probably much more due to certain affections, such as malaria and those consequent upon animal parasites, than to any const.i.tutional change that has taken place in the body, or any profound corresponding change in the mind.
It is a case of the body influencing the mind and producing an apparently different race from that which existed before, though all this may be changed for the better by some even slight amelioration of bodily conditions.
In any attempt, then, to influence the human mind in order to use its power and its reserve energy for therapeutic purposes, the place of the body and its influence upon the mind must always be remembered. It is quite impossible to lift people up to enable them to use their mental reserve force if they are living in discouraging physical conditions, which use up so much of energy as to make it impossible to have any to spare. Many of the phases of mental discouragement and lack of initiative which are reflected in what we call lowered resistive vitality and lack of immunity to infection, are really consequent upon physical states representing a drain upon the system that can be removed, or at least greatly improved, if they are discovered and properly treated. Victims of chronic malaria and of hook-worm disease cannot be lifted up by psychotherapy. Neither can sufferers from other forms of chronic physical debility. After the removal of the debilitating cause, however, mental influence may be brought to bear to encourage them to rise to their opportunities, to literally take on new life, and gradually acc.u.mulate reserve energy that will enable them to accomplish, not only the average work of mankind, but even better, in the reaction that comes with the new feeling of physical energy. And what is thus true in these extreme cases is even more true of minor ailments and conditions.
CHAPTER IV
THE MECHANISM OF THE INFLUENCE OF MIND ON BODY
The question as to how mind influences body, and body mind, has always proved a riddle to all but those with a special theory in the matter.
The facts of the mutual influence of mind on body are so obtruded on observation that they could never be missed, but it is quite another thing to reach a satisfactory explanation of them. How the will initiates motion continues in spite of all our advance in psychology, to be as much a mystery as ever. Just how sensation is transformed into ideas is a parallel mystery. Since the mind is able to influence motion, it is not surprising that it should be capable of modifying secretion or inhibiting other kinds of functions. Any of these various activities is scarcely more mysterious than the other. Since the transformation of sensation into thought takes place, it is comparatively easy to conclude that the mental processes are able to exclude, or to some extent inhibit, sensation. All these activities have actually been observed. How does this mutual influence of mind on body take place? What principles underlie it?
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At present, it would be futile to hope to outline the absolute principles on which the mechanism of mental influence or suggestion depends, but we can discuss recent explanations that have been offered, and this will help us to understand, not the mystery itself, but just where the mystery lies and what the physical mechanism connected with it is.
[Ill.u.s.tration: Fig. 2.--CORTEX OF HUMAN BRAIN ILl.u.s.tRATING COMPLEXITY OF THE SYSTEMS AND PLEXUSES OF NERVE FIBERS (Combination of the methods of Weigert and Golgi--after Andriezen). _c, z.,_ clear zone free from nerve fibers; _M.P.,_ Exner"s plexus in the molecular layer; _A. str.,_ ambiguous cell stratum; _Subm, P.,_ sub-molecular plexus; _Gt. P. P.,_ great pyramidal plexus; _Pol.
P.,_ polymorphic plexus; _W.,_ white matter. (Barker.) ]
{110}
These explanations are as yet only theoretic, but theories have often helped students in science to make their thoughts more concrete and their investigations more practical. It would be a mistake to conclude that because some of the theories advanced are very plausible, we have, therefore, reached definite truth with regard to the mechanics of the brain that underlie suggestion and mental influence.
Brain Complexity.--The most interesting feature of the discoveries in brain anatomy during the past generation, has been that the central nervous system is of even greater complexity than had been thought.
Because of this, these new discoveries, instead of solving the biological mystery they subtend, or even helping very much to solve it, have made it still harder to understand just how we succeed in controlling and directing this immensely complex machine, of whose details we are utterly unconscious, yet which we learn to use with such discriminating nicety of adjustment and accomplishment. The discoveries of Golgi and of Ramon y Cajal show us that the brain consists of nerve cells with a number of ramifying fibers connecting each cell and each group of cells with other simple and compound elements of the brain, and sending down connecting fibers to every organ and every part of the body. Dr. Ford Robertson calculates that in an average human brain there are at least three billions of cells.
Without knowing anything of their existence, much less anything of the infinite detail of their structure and mode of operation, we have learned to use these for many purposes.
[Ill.u.s.tration: FIG. 3.--SMALL AND MEDIUM-SIZED PYRAMIDAL CELLS OF THE VISUAL CORTEX OF A CHILD TWENTY DAYS OLD. Section taken from the neighborhood of the calcarine fissure. A. plexiform layer; B, layer of the little pyramid; C, layer of the medium-sized pyramid; a, descending axis cylinders; b, ascending or centripetal collaterals; c, stems of the giant pyramidal cells. (Ramon y Cajal.)
(This and the next three ill.u.s.trations ill.u.s.trate the complexity of the central nervous system as observed in the very young child where the development does not as yet obscure the interesting details of dentritic branching. They serve to emphasize the much more p.r.o.nounced condition which develops in the adult.)]
Nerve Impulses.--We do not know even how nerve impulses travel.
Probably they do so by a mode of vibration, just as heat and light and electricity are transmitted as modes of motion. The similarity that used to be thought to exist between the transmission of nerve impulses and of electrical energy is now known definitely to be only an a.n.a.logy, and not to represent anything closer. Waves of nervous energy travel at a different rate of speed from electrical waves, and there are other notable differences. Such phases as molecular action, or motion, or vibration are only cloaks for our ignorance, A generation ago Huxley declared that "the forces exerted by living matter are either identical with those existing in the inorganic world or are convertible into them." He instanced nervous energy as the most recondite of all, and {111} yet as being in some way or other a.s.sociated with the electrical processes of living beings. As Prof, Forel said in his "Hygiene of the Nerves," "the neurokym cannot be a simple physical wave, such as electricity, light or sound; if it were its exceedingly fine weak waves would soon exhaust themselves without causing the tremendous discharges which they actually call forth in the brain."
Law of Avalanche.--How great is the power of the nervous system or the energy of it that may be set loose by some very simple reflex, as suggested by Forel, is ill.u.s.trated by what Ramon y Cajal calls the Law of Avalanche. A single peripheral nerve ending is represented in many different portions of the brain. An ocular nerve ending, for instance, probably has direct connection with four or more portions of each hemisphere. Each of these portions of the brain has a.s.sociation fibers connecting it with other parts and so the stirring of a single nerve ending may disturb many thousands, perhaps hundreds of thousands, of brain cells; at least it affects them in some way or other. The older psychologists used to insist on the similarity, or a.n.a.logy, between the cosmos ol the universe and the microcosmos that man is. The English poet of the nineteenth century told us that there is no moving of a flower without the stirring of a star, so intimately connected by the laws of gravitation is the universe. In the microcosm something of this same thing is true and a t.i.tillation of even the most trivial nerve ending may produce, in Ramon y Cajal"s phrase, "an avalanche" of cell disturbances in the central nervous system which may seriously disturb the whole system.
What is thus true for the brain is true, also, for the cord, and the complexity of spinal cells needs to be seen to be properly realized.
[Ill.u.s.tration: Fig. 4.--SERIES OF SECTIONS SHOWING THE FINE NERVE ENDINGS AND BRANCHINGS OF THE FIRST AND SECOND LAYER OF THE VISUAL CORTEX OF A CHILD FIFTEEN DAYS OLD. A and B, very thick nerve plexus of the layer in which the little pyramids are contained; C, a plexus containing a series of branches that is less thick and intricate; D, small cells whose ascending axis-cylinders have resolved themselves into a set of similar branches; E, arachnoid star cells whose axis cylinders produce a thick plexus in the first layer; F and G, small cells with short axis cylinders that have very few branches. (Ramon y Cajal.)]
Psychic States.--There are a number of human states representing extremes of sensory and intellectual conditions in man, that have always attracted attention, and in recent years have been special objects of investigation by physiologists. Natural sleep is one of these; the unconsciousness of narcotism or anesthesia is another.
Hypnotism is allied to both of these, and would seem to lie on a plane between them. Then there are various states of exaltation in which sensations fail to produce their usual effect. Those {112} escaping from a fire, or pa.s.sing through a severe panic of any kind may sustain all manner of injuries without being aware of them. Martyrs, for all manner of causes, are able to withstand suffering with such equanimity, and sometimes even joy, that it is evident that they cannot feel, as would people under ordinary conditions, the pain that is being inflicted on them.
[Ill.u.s.tration: Fig. 5.--FIRST, SECOND AND THIRD LAYER OF THE ANTERIOR CENTRAL CONVOLUTION (THAT IS, OF THE ASCENDING FRONTAL CONVOLUTION) OF THE BRAIN OF A CHILD ONE MONTH OLD. A, B, and C, little pyramids; D and E, medium-sized pyramids; F, cells with two sets of tufts; their axis cylinders resolved into end tufts; G, protoplasmic layer that comes from one of the large pyramids of the fourth layer; H and I, fine dentrites of the cells of the sixth and seventh layer; J, small cells with two end tufts; K, spindle cells with long axis cylinder. (Raymon y Cajal.)]
[Ill.u.s.tration: FIG. 6.--LAYERS OF THE POSTERIOR CENTRAL OR ASCENDING PARIETAL CONVOLUTION OF A NEWBORN CHILD. 1. plexiform layer; 2.
small pyramids; 3. medium-sized pyramids; 4. external large pyramids; 5. small pyramids and star shaped cells; 6, deep layer of large pyramids; 7, spindle and triangular shaped cells. (Raymon y Cajal.)]
In the midst of intense mental preoccupation one may hold so cramped a position as would be quite impossible for the same length of time with the faculties normally engaged. There are pathological conditions, like hysteria, in which the pain and fatigue sense may, for a time at least, be quite in abeyance.
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[Ill.u.s.tration: FIG. 7.--DIAGRAM OF CELLS OF CEREBRAL CORTEX (after Starr, Strong and Leaming). I, superficial layer; a, fusiform; b, triangular; c, polygonal cells of Ramon y Cajal; II, layer of small pyramids; d, smallest; e, small; f, medium-sized pyramidal cells with axones descending to the white matter and giving off collaterals in their course; III, layer of large pyramidal cells; g, largest (giant) pyramidal cells; k, large pyramidal cells with very numerous dendrites; all pyramidal cells are seen to send long apical dendrites up to I; m, Martinotti cell with descending dendrites and ascending axone; n, polygonal cells; IV, deep layer; p, fusiform cell; q, polygonal cell; V, the white matter containing the axones from the pyramidal cells, d, e, f, g, and from a cell of the deep layer q; r, neuroglia fibers. (Barker.)]
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[Ill.u.s.tration: Fig. 8.--SCHEME OF LOWER MOTOR NEURON. The motor-cell body, with protoplasmic processes, axis cylinder, side fibrils or collaterals, and end ramifications, represents parts of a neuron. a.
h., axon hillock devoid of Nissl bodies, showing fibrillation; ax., axon. This process near the cell body becomes surrounded by myelin, m., and a cellular sheath, the neurilemma (not an integral part of the neuron); c, cytoplasm showing Nissl bodies and lighter ground substance; d, protoplasmic processes (dendrites) containing Nissl bodies; n., nucleus; n., nucleolus: n. r., node of Ranvier; s. f., side fibril; n. of n., nucleus of neurilemma; tel., motor end plate or telodendrion; m., striped muscle fiber; s. l., segmentation of Lautermann. (Barker.)]
Neurons.--With the advance in our knowledge of brain anatomy, various explanations for these curious conditions have been suggested. The discovery that the central nervous system is composed of a large number of separate units, and not of a feltwork of continuous fibers with cells here and there, revolutionized all previous attempts at explanation of these conditions. We know now that it is not fibers but cells that are the most important components of the brain and spinal-cord substance, and that, indeed, the fibers are only prolongations of cells. The central nervous system is made up of nerve cells with various appendages, and each one of these cells and its appendages is called a neuron. These appendages are of two kinds, one the axon, the long conducting fiber which transmits the nerve force of the cell, the other the dendrons or connecting elements by which the cell is linked with the axon of another cell. The contact of the axon of one neuron with the dendrons of another is called a synapse. Each neuron does not extend to and from the brain and the periphery, but series of neurons connect the surface of the body with the brain.
There is usually a group of neurons in the path from the surface to the brain cortex. The peripheral neuron for sensation runs from the surface of the body to the spinal cord, while for motion it runs in the opposite direction. There is a secondary neuron in each chain that runs up or down the spinal cord to and from the base of the brain. A third--sometimes, perhaps, a fourth--neuron connects in the two directions, afferent and efferent, the cortex and the base of the brain.
_Neuronic Movement_.--Duval, the French anatomist and histologist, suggested the possibility of voluntary and involuntary movement in the neurons or nerve cells themselves, thus making and breaking connections.
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[Ill.u.s.tration: FIG. 9.--SCHEME OF THE VISUAL CONDUCTION PATHS (after C. von Monakow). a, rods and cones; b, rods; c, nuclei of rods; d, bipolar cells for the cones; e, bipolar cells for the rods; f, large multipolar ganglion cells giving rise to the axons of the N.
opticus; g, centrifugal axon of a neuron, the cell body of which is situated in the collieulus superior, its telodendron being situated in the retina; h, Golgi cell of Type II, or dendraxon in the corpus geniculatum laterale; i, neuron connecting the corpus geniculatum laterale with the lobus occipitalis, its axon running in the radiato occipito-thalamica (Gratioleti). The visual impulses are indicated by the arrow. (Barker)]
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[Ill.u.s.tration: FIG. 10.--SCHEMATIC FRONTAL SECTION THROUGH THE OCCIPITAL LOBE ILl.u.s.tRATING MANIFOLD CONNECTIONS IN A SINGLE LOBE (after H. Sachs), v, cornu posterius ventriculi lateralis; f. c, fissura calcarina; b, upper division: i, lower division; coll, sulcus collateralis; s. o. I, sulcus occipitalis superior (fissura interparietalis); s. o. II, sulcus occipitalis medius; s. o. III, sulcus occipitalis inferior; c. a., calcar avis; g. l., gyrus lingualis; g. f., gyrus fusiformis; g. o. s., gyrus occipitalis superior; g. o. m., gyrus occipitalis medius; g. o. i.. gyrus occipitalis inferior; c, cuneus; 1-10, forceps; 11-14, stratum sagittale internum: 15, stratum sagittale externum; 16, stratum calcarinum; 17, stratum cunei transversum; 18, stratum proprium cunei; 19, stratum proprium s. o. I; 20, stratum proprium s. o. II; 21, stratum proprium. s. o. III; 22, stratum proprium, s. coll.; 23, stratum profundum convexitatis. (Barker.)]