Part 3

This leads the writer on to the discussion of this singular hæmorrhagic process principally characteristic of viperine poisoning, and only very exceptionally produced by the poison of colubrines. It is among the symptoms of snakebite poisoning one of the most interesting ones, but also one most difficult of explanation. There can be no doubt that it is produced by vaso-motor paresis and paralysis. We further know that it is preceded by dilatation of the capillaries and small veins, and that it is effected principally through the process known as diapedesis, or the passage of both red and white corpuscles with plasma through the unruptured capillary membrane, and even the thin one of small veins, which is nearly of the same structure, being composed of endothelial cells united by cement. This membrane possesses a certain degree of porosity, which is probably increased by dilatation. In the absence of plain muscular fibres contraction and dilatation of the capillaries can only be effected by a corresponding contraction and expansion of the nuclei of the endothelial cells. As fibrils derived from non-medullated nerves terminate in small end-butts in connection with the capillary membrane, we may assume that the nuclei of the endothelial cells are under the sway of vaso-motor nerve currents, that weak ones will expand, strong ones contract them. We may further assume that the red and white corpuscles force their way out of the vessels through pores in the cement substance, since a passage of cell through cell is not thinkable. Thus far we see our way fairly clear. But the question now arises: what causes the solid constituents of the blood to force their way through the capillary membranes all over the mucous surfaces, even the conjunctiva, and not these alone, but also through serous membranes such as the pericardium, and strangest of all, through old scars in the skin? If the most modern ideas as to the cause of diapedesis being blood pressure are correct, it is quite incomprehensible how it can take place in the absence of blood pressure, and take place so extensively. The theory of blood pressure may apply to diapedesis accompanying the inflammatory process. In snakebite poisoning it is more likely to be due to passive engorgement of the capillary system and probably also to blockage of corpuscles in the finest capillary tubes. In vaso-motor paresis, and still more paralysis, the arterioles supplying the capillaries are widely dilated, and at the lowest blood pressure probably send more blood into the latter than in the normal state. This circumstance in itself is apt to cause capillary engorgement. In the finest capillaries permitting only a string of corpuscles, one behind the other but none abreast, to pass through in the normal state, dilatation may cause blockage by two or three becoming wedged in abreast and closing the lumen of the vessel by a sort of embolism. On the arterial side of this obstruction the crowded corpuscles force their way through the porous cement substance by what little "vis a tergo" there may be left yet, whilst in the venous side, in the small veins corresponding with the closed capillaries, engorgement must necessarily take place through this "vis a tergo" being entirely absent, and diapedesis, which here also has been observed, follow in due course. The writer has always been inclined to take this view, the correctness of which appears to be borne out by an experiment recorded by Feoktistow. He found on sprinkling a two per cent. solution of snake-poison over the mesentery of an healthy animal, that wherever a drop of the solution fell, almost immediately the capillaries and small veins became dilated and small point-like effusions of blood appeared, gradually enlarging and ultimately becoming confluent with adjoining ones. Large hæmorrhagic surfaces were thus formed in a comparatively short time. Here paralysis of the nerve-cells interspersed in the vaso-motor nerve-ends was evidently the first effect, followed by dilatation of the capillaries and immediately afterwards by effusion. Without some obstruction within the capillaries, like that above described, effusion in this purely local poisoning process appears unexplainable.

The special preference which the viper-poison has for the vaso-motor sphere will hereafter be referred to. Hæmorrhages from Australian snake-poison are comparatively rare. Even at the bitten place there is as a rule very little swelling and effusion and frequently none at all. When it occurs it quickly disappears after strychnine injections. Only a few cases have been reported as yet of blood-vomiting. In one of these the hæmorrhage took place soon after the bite and was so considerable that it must have arisen from actual rupture of vessels consequent on abdominal engorgement and not from mere diapedesis. It is very doubtful whether the latter ever takes place here as it does after viper-bite in India and elsewhere. Even the death-adder, although half a viper, and producing more swelling and effusion locally than any other one of our snakes, is not known to have ever produced the extensive effusions from mucous surfaces in pericardium, lungs, &c., described above. More research however is necessary, especially more carefully conducted autopsies. Since Australia has taken the lead in this hitherto so obscure department, every practitioner should make it his object and special ambition to contribute his quota towards the elucidation of the subject, not only by reporting successful cases, but also the post-mortem appearances in unsuccessful ones, wherever it is practicable. It is not by experiments on animals but by a hearty co-operation of Australian practitioners that we can ever hope to supplement our knowledge on this subject.

b.--The Respiratory Centre.

Paresis of this centre does not play as important a part here as it does in India, more especially after cobra-bite. The peculiar, and as yet unexplained, tendency of snake-poison to act with special virulence on some centres, passing others by comparatively little disturbed, is markedly shown by the cobra poison of India as compared with that of our Australian cobra (_hoplocephalus curtus._) The unfortunate victims of the former are tortured by an ever-increasing dyspnoca, and finally die from asphyxia, under what are supposed to be carbonic acid convulsions. They retain their consciousness more or less unclouded to the last, the poison spending all its force on the respiratory centre, and leaving the brain intact. Here we hardly ever see actual dyspnoca after the bite of hoplocephalus or any other Australian snake. Respiration becomes quicker at an early stage, and then, from hour to hour, shallower; but our patients soon pass from sleep into coma, and suffer no respiratory distress even when, in consequence of general paralysis, the respiratory muscles cease to act, which usually takes place a few minutes before the heart stands still.

Feoktistow records the following observations on cats with reference to the respiratory centre:--Small intravenous injections of the fresh poison (0.07-0.13 mllgr.) produced a great increase in frequency of respirations (280-360 per minute). Section of both vagi at once reduced this frequency, from which he infers that small doses act as an irritant to the respiratory centre. When small doses were repeated several times, the respiratory movements were gradually retarded, and asphyxia set in through paralysis of the centre. Large doses produced this effect at once, without any previous acceleration. Very large ones paralysed respiration, heart, and vaso-motors almost simultaneously, and caused the blood pressure to fall to 0. By the kymograph respirations were found to become shallower in proportion to their frequency. As the latter was reduced, they became at first deeper, but ere long shallower again, and were occasionally interrupted by spasmodic inspirations. Artificial respiration prolonged life for a short time only.

C.--Action on Centres of Cranial Nerves.

Among the symptoms denoting paresis of motor-centres of cranial nerves, together with sympathetic ganglia, the first and most noteworthy is the early dilatation of the pupil. This truly pathognomic condition is never absent, and becomes intense when paresis becomes intensified into paralysis. The most glaring light, in immediate proximity to the eyeball, has then no effect whatever on the pupil. If it remains dilated after strychnine injections have restored consciousness and the power to walk, it is a sure sign that the snake-poison is not completely counteracted, and will in all probability re-assert itself, necessitating another injection, whilst a pupil restored to its normal condition justifies the conclusion that the patient is safe.

Another symptom denoting paresis of the cranial nerve-centres is a marked change in the expression of the face. The features become relaxed, and lose their mimetic play. The cornea is dull, and, together with the anterior surface of the eyeball, becomes dry, as the eyelids are moved imperfectly, if at all, and the tears in consequence are not properly distributed over the conjunctiva. The nostrils become more or less immovable, and the naso-labial fold is obliterated, whilst the lower lip hangs down. The lips are apart, as the lower jaw is not held up by the muscles. When paralysis supervenes it drops entirely, and the tongue protrudes.

Deglutition, somewhat difficult in paresis, is completely suspended in the paralytic stage, through paralysis of the soft palate, the pharynx, and oesophagus. Liquids forced on the patient in this extremity may partly flow down the oesophagus, but will also enter the larynx, and their administration should be carefully avoided.

D. Action on motor-centres of Cerebellum and Basal Ganglia.

Of this action little if anything is patent to observation. A certain want of co-ordination in the movements has been noticed in the early stage of paresis, and the peculiar staggering walk of persons in this stage is probably owing to an affection of the motor-centres of the cerebellum. That they do not escape the action of the subtle poison, when symptoms denoting the invasion of all the other motor-centres throughout the body are in evidence, we have every reason to assume. The co-ordination and automatic regulation of the lower motor-centres must necessarily escape observation when the function of these centres is partially suspended, and when, moreover, the powerful currents of nerve force the cerebellum and basal ganglia receive from the motor cortical centres of the cerebrum are partially if not wholly withdrawn.

E. Action of the Motor Cortical Centres of the Cerebrum.

In all but the very lightest cases of snakebite-poisoning there are always symptoms manifested that cannot be referred to any other cause than an invasion of the centres now under consideration. They range from mere stupor, confusion of thought and delirium to the deepest coma, with complete extinction of consciousness and insensibility to all external impressions. Coma is a frequent and in serious cases an almost invariable symptom in Australia. After the bite of our death adder only we find persons sometimes collapse and expire suddenly, when still conscious and able to answer questions rationally. Coma invariably develops from sleep. It is, in fact, sleep intensified. An almost irresistible desire to sleep is one of the first symptoms to be observed. If the dose of poison imparted by the snake has been small, the desire may pass off or the sleep may not assume the form of coma, but in all serious cases it quickly assumes that form. _Vice versa_ the deepest coma becomes sleep again, when the suspended function of the cortical centres is roused by strychnine injections. The insensible and completely paralysed patient usually announces the gradual return of consciousness by a few groans and uneasy movements and not unfrequently begins to snore, as in ordinary sleep, when a smart shake at the shoulder will rouse him into full consciousness. At other times this transition from coma back to sleep does not take place and consciousness returns quite suddenly, the persons opening their eyes and looking around them, dazed and bewildered, but perfectly conscious at once. When coma is fully established and the largest and most powerful motor-centres have succumbed to the insidious poison, general paresis becomes general paralysis and all the motor-centres of the body are in a condition of more or less suspended functional activity. This and this only is the condition of the centres, the whole secret of snake-poison, that has puzzled the human mind for ages and yet appears so simple when discovered at last. It is beautifully and strikingly illustrated in the phenomena before us. We have coma and complete general paralysis, every motor-nerve cell, from the highest psycho-motor one downwards, is thrown into a state of torpor and has ceased to discharge the life force that regulates every process of life and the entire absence of which inevitably must be death. Only weak, lingering currents are sent forth yet and put off the inevitable finale for a time. But the strychnine is injected and mark the change. It courses quickly to every one of the sleepers, for whom it also has an affinity, but the direct opposite to that of the deadly venom that has overpowered them. It touches them as if with the wand of a magician and orders them to awake and do their work. There is no disobeying the mandate, for it is founded on one of nature's unchangeable laws. Almost immediately the cells begin their work again, the life streams flow afresh, coma and paralysis vanish and within a very short time the subject of this beautiful experiment is snatched from the brink of the grave and restored to life and health.

The phenomena of sleep and coma as the result of a poison acting as a depressant of motor nerve force afford food for some interesting speculations, which, however, as more concerning the psychologist, the writer can only glance at here. It is evident that in the highest of psycho-motor centres, the organs of thought and of consciousness, the paresis of the lower centres assumes the form of sleep, and paralysis that of coma. Sleep, as a partial, and coma, as a complete, obliteration of thought and consciousness must, therefore, be intimately connected with motor nerve function, sleep being a reduction, coma a suppression of the function, or a suspension of thought. Ideation, to use J. S. Mill's very appropriate term for the thought process, appears to be effected by motor nerve currents or, at all events, to be accompanied by them and suspended with their suspension. The thinking principle, the nous within us, is no doubt more than mere nerve action, but it can, apparently, not manifest its presence without motor nerve cells in healthy action. Every thought, though not synonymous, is evidently synchronous with a current of motor nerve force, and it is not improbable that, by means of these currents, that silent transference of thought is effected from brain to brain, which modern psychology has demonstrated to be not only possible but actual under certain conditions. But further speculation on these interesting mysteries it would be out of place here to indulge in.

F. Action on Sensory Centres and the Reflexes.

The sensory sphere remains comparatively unaffected in mild cases, and in the early stages of more serious ones, but when paresis has deepened into paralysis, sensation becomes ever more blunted, and with the advent of coma, of course, quite extinct. Reflexes, both superficial and deep ones, are also completely abolished at this period of the poisoning process, and the nerves of special sense do not react against any, even the strongest possible stimulation. The eye stares vacantly into a glaring light held close before it, and the widely dilated pupil shows no sign of reaction. The ear also appears deaf to any noise, and strong ammonia vapour is inhaled through the nose like the purest air, whilst pricking, beating, and even burning the skin elicit not a quiver of a muscle.

Feoktistow's experiments with regard to reflexes, more especially their restoration by strychnine, differ in their results entirely from Australian observations. Whilst we have no difficulty in restoring them with the drug on man as well as the domestic animals, his experiments on frogs were a failure, and merely showed a decided antagonism between the two poisons. He did not succeed in restoring the reflexes, and, instead of following up with experiments on the higher animals, he trusted implicitly to his results on frogs, and thus lost his opportunity.

G. Irregularities in the Action of Snake-poison.

There is in the whole range of toxicology not a single condition known to us in which the symptoms, both in chronological order and in their strength and relation to each other, show as much variety as those of snake-poison. Experienced observers will agree with the writer that it is but rarely we find two cases of snakebite exactly alike in the symptoms they present. Some of these puzzling variations have already been alluded to, but it is necessary to consider them a little more in detail. Apart from quantitative differences in the poison imparted, they arise principally from the strange capriciousness with which the poison concentrates its action on special nerve centres and leaves others comparatively intact.

The nearest approach to regularity and orderly sequence of the symptoms, as described in the foregoing pages, we find in Australia after the bite of the tiger snake (_Hoplocephalus curtus_) and the brown snake (_Diemenia superciliosa_), more especially that of Queensland. Here we can trace the action of the poison distinctly from centre to centre, from the lowest part of the anterior cornua up to the cortex cerebri, and even throughout the sympathetic ganglia as far as they are patent to observation. The poison of these snakes is extremely diffusible and quickly absorbed. It spreads with rapidity and nearly equal force over all the motor centres, the symptoms following each other so quickly as almost to appear simultaneous, though, in reality, successive. But even the poison of these snakes leaves the arms only slightly paretic, when paralysis in all the other voluntary muscles is well pronounced, and does not paralyse them until coma has set in. It also touches the respiratory centre but slightly. Sometimes coma is light and the patients can be roused for a little while, at other times it is deep and lasts till death. But even greater variations are observed occasionally. In one very extraordinary case of tiger snakebite, the patient, a child of 9 years, remained conscious to the last, and after vomiting blood freely died under symptoms of heart failure. In rare cases the symptoms resemble those of cobra poison.

If we turn from these to the black snake (_Pseudechis porphyriacus_) a different picture presents itself. Its poison does not produce so deep a coma and often none at all. The patients generally feel drowsy and fall asleep, but are easily roused and sometimes awake spontaneously. There is also not the same amount of muscular paralysis. They are frequently able to walk a few steps with assistance and can move in bed, the arms especially being almost free from paresis. But the insidious poison none the less does its work, though its effects are less patent. It concentrates its action on the vaso-motor centre. The victims from hour to hour become more anæmic in appearance through increasing engorgement of the abdominal veins. Anæmia of the nerve-centres hastens the collapse, and from the combined effects of this and heart failure death takes place suddenly and quickly as if in a fainting fit. Here then we have an approach to the effects of viper poison which is also shown in the greater amount of swelling and effusion around the bite and in the bitten limb.

This approach is still closer in the poison of the death adder (_Acantophis antarctica_). There is generally much extravasation of blood locally. Muscular paralysis is also less pronounced, but sudden collapse from vaso-motor paralysis not unfrequently takes place, when the patients fully conscious are still able to sit up. That leading feature of viper poison, diapedesis with hæmorrhage, does not occur with either.

If we turn from Australian to Indian snakes, the peculiar tendency of the poison to concentrate its action on special nerve-centres becomes still more marked. The predilection of the cobra poison for the respiratory centre has already been dwelt on. More remarkable and strange is the action of the Indian viper-poison on the minute ganglia in the vaso-motor nerve ends, which control the capillary circulation, and by their paralysis bring about extensive hæmorrhage through diapedesis.

It is quite impossible for us with our present scanty knowledge to account for these peculiarities and irregularities in the action of a poison, which we know now to accomplish its destruction of animal life by one uniform design and principle of action. That the protean forms under which the poison-symptoms present themselves are one and all the result of reduction and suspension of motor nerve currents may now be accepted as a well proven and fully established scientific fact. But why the effects of one and the same cause are so varying in their appearance, why the poison of different varieties of snakes, and even that of the same variety under different circumstances, make such a capricious selection among the various motor nerve-centres we can not explain and probably never will. Chemical analysis of the dead poison, no matter how minutely and elaborately it may be effected, will probably never throw much light on the "why" of this strange puzzle, for the subtle phenomena of life are apt to elude the grasp of the analyst. We have to do with a poison transferred from one living organism into another one and modified in its action by the condition of the giver and the constitution and peculiarities of the recipient quite as much probably as by slight variations in its chemical composition. Accepting the "why" of these phenomena like that of many other ones, simply as a fact not to be accounted for at present, we must be content to know "how" they are effected, and, what is of more immediate and paramount importance to know, that we now have an antidote that will deal successfully with them all, that the convulsions and hæmorrhages of the Indian viper-poison and the asphyxia of that of the cobra will yield as readily to strychnine, when properly and boldly applied, as the coma and general paralysis following the bite of the deadly tiger snake.

THE ANTIDOTE.

The theory of the action of snake-poison as that of a specific nerve-poison, depressing and more or less suspending the function of the motor nerve-centres throughout the body, has in the foregoing pages received a double proof of its correctness.

In the first place, all the symptoms the snake-poison produces have been passed in review, and shown to be fully explainable by this theory. On this ground alone it may be claimed to have been fully established; for it is an axiom in science that a theory on any subject must be accepted as correct, if it accounts satisfactorily for all the phenomena observable in connection with that subject by showing them to result from the operation of one law. The second inductive proof of the correctness of the writer's theory has been rendered by the experiments of Feoktistow on animals.