Popular Science Monthly/Volume 12/April 1878/Poisons of the Intelligence-Chloroform
By CHARLES RICHET.
CHLOROFORM is a colorless, volatile, oily liquid; it is denser than water, and does not mix with it. It was discovered by Soubeiran in 1831, and Soubeiran's process for obtaining it is still in use, viz., distilling alcohol with calcium hypochlorite and lime. The hypnotic properties of chloroform were discovered in 1847 by Flourens, a few months after Jackson had recognized similar properties in ether; but the first surgeon who made use of it in an operation on the human subject was Simpson, of Edinburgh, in November, 1847. Since then, the use of chloroform has become so general, that nowadays no great operation in surgery is attempted without employing it. We may, therefore, justly regard the discovery of surgical anæsthesia as one of the greatest scientific achievements of the present century, so fruitful of benefits to the human race.
The principal effect of chloroform is the paralysis of sensibility, or anæsthesia. In so far forth it acts upon the mind, for sensibility is only one of the forms of mind; but this point, which as yet is rather obscure, calls for a few words of explanation.
Two great functions devolve upon the nervous system, sensibility and motion: it is through sensibility that we receive impressions from without; and it is through the excitation of the muscles, or movement, that we manifest our will, or act upon external objects. In the absence of both disease and poisoning, the will—that is, the mind—excites, through the spinal cord, the various muscles, producing movement; but this condition is not absolutely necessary, since in decapitated animals, for instance, the nervous system of the spinal cord can of itself produce motion of the muscles. Here we have motor activity, but no sensibility. Sensibility exists only where the mind is intact and capable of perceiving, so that a creature which has no mind is void of sensibility. This fact is confirmed by pathological observation; for, whenever the mind is affected, there appear at the same time symptoms of disordered sensibility, and vice versa. And when we find a patient exhibiting notable disorder of the sensibility, then, if the nerves are intact, we can safely conclude that the central nervous system is affected, and to that degree that the mind has not escaped.
Anatomy and physiology here are in accord with pathology. Some animals possess little or no sensibility: they belong to the lower grades of animals; their intelligence is obscure, and their sensibility is as obtuse as their intelligence. On the other hand, if we consider animals of higher intelligence, we find their sensibility becoming more and more keen, till we come to man, at once the most intelligent and the most sensitive of animals. And even in man himself we find race differences, those races being most sensitive which possess the highest decree of intelligence. The anatomical structure of the nervous centres is in harmony with this coincidence, for it is in man that the posterior columns of the spinal cord are most voluminous, as compared with the anterior. Now, the anterior columns transmit the motor excitations to the nerves, while the posterior columns transmit the sensory excitations. Again, the posterior lobes of the brain in man, as compared with animals, are more developed than the anterior. But it is in the posterior lobes that perception of sensitive excitations appears to reside.
Nor is it surprising that there should exist so intimate a relation between mind and sensibility. Indeed, whatever may be the influence of the spontaneous development of the mind itself, resulting from the constitution of the brain, which is its organ, it still holds true that all our knowledge comes from our sensations, and from the brain-work thence resulting. Mind is, so to speak, the product of these two factors; and our notions of the world around us, elaborated and fecundated by the mind's spontaneous action, constitute individual personality. Hence, inasmuch as anatomy, physiology, and pathology, show intimate relation between sensibility and intelligence, we can justly say that psychology confirms the positive data furnished by these three sciences.
Accordingly, poisons which affect the intelligence are ipso facto poisons of the sensibility. In this respect alcohol does not differ from chloroform. When alcoholic intoxication is only beginning, we find already a notable degree of insensibility; but at the comatose stage the insensibility is total, just as in the last stage of chloroform. Thus intoxication by chloroform and intoxication by alcohol proceed along parallel lines, and we can distinguish a first period of intoxication, properly so called, and a second period of sleep or coma.
When a person takes chloroform, the first few inhalations make him dizzy; he is seized with a sort of vertigo and dimness of vision. This vertigo goes on increasing, and, as the patient continues to respire the toxic agent, his ideas become more and more exalted. He hears what is said to him and makes replies, but he does so after the manner of a drunken man, at first exaggerating his impressions and regardless of proportion. His judgment has already disappeared, and he utters the most insignificant replies with a theatrical accent, the effect being often grotesque. Next, his ideas grow more and more mixed: will and judgment being gone, ideation is disordered and delirious; in short, we have a state of sleep accompanied with dreaming, closely resembling ordinary sleep.
When the chloroform absorbed by the mucous membrane of the lungs has passed into the blood, active memory, which presupposes attention and will, has disappeared; still, the intelligence is not yet dead. Ideas are still conceived, old recollections persist, and sometimes even the memory of past events is strangely quickened. The patient will speak in a language he thought he had forgotten, and recall old stories that seemed to have passed into oblivion. This superexcitation of memory is all the more interesting because in sundry forms of mental alienation it occurs with the same characters—these, too, being accompanied by entire loss of active memory.
Though insensibility supervenes very soon after the administration of chloroform, commonly it occurs only after the loss of memory, and this circumstance leads to very singular results. Thus, if the surgeon begins the operation before perfect insensibility has been produced, the patient will cry out, and beg to have it delayed till the drug has had full influence. One might suppose, from his cries of pain and his contortions, that the chloroform had produced no effect, and yet on awaking he has no recollection of what has taken place.
Is that real pain which leaves in the mind no trace? The answer to this question is not so easy as one might imagine. Suppose an acute, penetrating pain, continuing only for about one minute. Undoubtedly the patient suffers real pain during that minute; but, if all memory of it disappeared at once, then the patient would deny that he had suffered at all, and would not hesitate to undergo the operation again. In short, he would have enjoyed the benefits of chloroformic anæsthesia.
In administering chloroform, we must take account of the patient's temperament. If he is a resolute, courageous person, all will go on well, and the insensibility will readily disappear; if, on the contrary, he has an unconquerable dread of the operation, great watchfulness will be necessary, for in such cases syncope is very frequent. Besides, such a patient resists the action of the drug for a long time, and it must be administered in far greater quantity than in the other case. The chloroform always retains its power, but the cerebral excitation to which some patients are subject enables them to resist its toxic action, as though the will could, so to speak, brace itself up to resist the action of the poison on the nerve-centres. The same occurs in the use of alcohol. One who will not be intoxicated may drink a large quantity without being drunk. At length, however, his will is conquered, and he falls to the ground, but he will not have experienced the exhilaration, the mad excitation, of the man who gives himself up to the influence of the liquor.
Thus, then, under the action of chloroform we find an antagonism existing between the various intellectual faculties—on the one hand the voluntary, and on the other the unconscious faculties. The latter are slowest to disappear; ideation, its guide and check, being deranged or destroyed, follows its habitual laws: association of ideas persists. External sensations are still borne in upon the mind, each one awaking a long series of ideas. As the sense of hearing is the last to disappear, the patient, though he can no longer either see or feel, hears every word that is spoken, and is set a-thinking at once. The same thing occurs in ordinary sleep, rarely in adults, but very frequently in young children. In fact, a certain degree of natural somnambulism is nearly always to be found in children. The child speaks out aloud without waking, he laughs and talks; more frequently he is frightened and cries. The course of his thoughts may be altered, diverted into another channel, by speaking to him gently, and this without arousing him from sleep. On awaking, all recollection of this has vanished. This method has been tried in mental alienation, to divert the thoughts of melancholies and hypochondriacs.
But soon these external phenomena which indicate the preservation of the intelligence, if not its integrity, disappear in their turn. The period of excitation is succeeded by the period of relaxation, and then the patient is in a deep sleep. However violent the external excitations, however painful the surgical operation, nothing can arouse the patient out of the comatose state into which he has fallen. His respiration is regular, his pulse slow and full, his pupils are motionless, and his features, paralyzed as it were, no longer wear that convulsive grimace which may be regarded as the last trace of sensibility. Intelligence is now destroyed. The coma of chloroform and that of alcohol appear to be essentially one. And, yet, what a difference! The former saves man from pain, the latter drags man down to the lowest depths of degradation; yet in both all signs of intellectual life have disappeared—there is a temporary death of the mind. It may be that, in the inmost nerve-tissues, brain-work still goes on, unconscious and silent, but whether this is so we know not.