So long ago as 1884, de Lacerda, in his “Leçons sur le venin des serpents du Brésil,” described the results of his researches upon the diastasic actions of venom. He proved that venom emulsifies fats, causes milk to curdle, and does not saccharise starch. But the solutions of venom employed by this author were not sterile, so that putrefactive phenomena may be believed to have occurred in the course of his experiments.
The subject has been studied afresh by Wehrmann60in my laboratory, and afterwards by Lannoy.61These two investigatorshave shown that venoms do not hydrolyse either starch or inulin.Cobra-venom and that ofViperachange saccharose very slightly. They do not modify the glucosides (amygdalin, coniferin, salicin, arbutin, and digitalin); they therefore do not contain emulsin.
On the other hand, these venoms possess, as I have already stated, very interestingkinasicproperties, which have been pointed out by Delezenne.62They consist in the fact that while venom alone is incapable of digesting cooked albumin, we have only to add to a pancreatic juice, in itself devoid of effect upon albumin, a trace of venom, to see this albumin immediately become digested.
Lachesis-venom is especially active in this respect. In Delezenne’s experiments it was generally sufficient to add to 1 c.c. of inactive pancreatic juice, 0·5 to 1 c.c. of a 1 in 1,000 solution, that is 0·5 to 1 milligramme of venom, to obtain the digestion of a cube of albumin weighing 0·5 gramme in the space of from ten to twelve hours. Much weaker doses, ⅕, ⅒, sometimes even1/80of a milligramme still gave the same result, with this sole difference that digestion took twenty-four, forty-eight, and even seventy-two hours to become complete.
Cobra-venom was found to be a little less active than the foregoing, but still its action was usually evident enough when it was employed in a dose of 0·5 milligramme or even 0·1 milligramme. As for the venom ofVipera berus, it was often necessary to employ it in doses from five to ten times stronger in order to obtain the same result.
Delezenne has ascertained, on the other hand, that these venoms entirely lose their kinasic power when they are subjected to ebullition for fifteen minutes.
Thiskinaseor diastase, capable of quickening the inert pancreatic juice, must evidently be of very great utility to the reptile in enabling it to digest its prey. Venom, therefore, is not, as has long been believed, a purely defensive secretion; it corresponds to a physiological necessity, like that of the intestinal orpancreatic juice. Herein is to be found the explanation of the fact that the non-poisonous snakes, although destitute of organs of inoculation, possess supralabial or parotid glands which produce venomous saliva.
Experiments have been made by Ch. Féré63to determine the effect upon the development of the embryo of the introduction of venom into the albumen of the egg of the fowl. He found that 83 per cent. of the embryos, developed in eggs intoxicated with 0·05 milligramme of viper-venom and opened after being incubated for seventy-two hours, exhibited various anomalies in development.
Venoms are modified or destroyed by certain normal diastases of the organism. It was shown long ago by Lacerda, Weir Mitchell, Sir Joseph Fayrer, and Lauder Brunton, that it is possible to introduce without danger into the stomachs of adult animals amounts of venom many times greater than the lethal dose. I have repeatedly verified this, but have nevertheless observed that young mammals, while being suckled, readily absorb venom by their alimentary canal, and succumb to the ingestion of doses scarcely larger than those which kill when subcutaneously injected. Here we have a very important fact, which once more proves how easily the intestinal mucous membrane of young animals is permeated by toxins. By my instructions Wehrmann64and Carrière,65in my laboratory, have studied the modifications undergone by venoms in the alimentary canal of rabbits. We have seen that these animals can ingest without inconvenience doses of venom 600 times greater than the lethal dose, and that, if we cause these ingestions to be repeated several times, contrary to the assertion of Fraser66(ofEdinburgh), we never succeed in obtaining immunity to the subcutaneous injection of a simple lethal dose, and no antitoxin is formed in the blood.
Theptyalinof the saliva,pancreatic juice, andbiledestroyCobra-venomin vitro. We must, therefore, assume that these diastases are veritable agents of destruction for ingested venom. The intestinal microbes play no part, any more than the intestinal juice by itself. The gastric juice has very little effect. Papain is almost as active as the pancreatic juice.
It had already been proved by Fraser, so long ago as 1895, that bile, after prolonged contact and in a sufficient dose, has a strongly destructive effect upon Cobra-venom; but, contrary to the opinion of this investigator, it is not antitoxic, for it possesses no preventive or curative property, and its effects are produced onlyin vitro.
We see from what has been stated above, that venoms introduced into a sensitive organism are capable of producing extremely complex effects upon the various tissues or humours. They act on the nerve-cells by theirneurotoxin, on the endothelium of the blood-vessels by theirhæmorrhagin(Flexner and Noguchi), on the red corpuscles by theirhæmolysin, on the fibrin of the blood and muscles by theirproteolytic diastase, and on the fibrin-ferment itself by theirthrombase.
They also act on the leucocytes, according to the experiments of Chatenay,67performed under the direction of Metschnikoff, and according to those of Flexner and Noguchi,68already cited.
Thus we understand how complex must likewise be the means of defence that have to be employed in order to afford an effective protection against such poisons.
The slightly intoxicated organism at first reacts by the intervention of the leucocytes; ahyperleucocytosisis produced, accompaniedby a more or less considerable rise of temperature. After a few hours everything returns to its normal condition, and if the injection of a lethal dose of venom is repeated several times, at intervals of a few days, it is not long before antitoxic substances are found to appear in the serum.
When the dose of venom injected is sufficient to cause death, we observe, a very few moments after the injection, alowering of temperatureand ahypoleucocytosis, which is the more pronounced in proportion to the nearness of the dose of venom to the minimal lethal dose. With very strong doses the hypoleucocytosis has not time to manifest itself.
It is therefore probable that, in intoxication by venoms as in that by the toxins of micro-organisms, the protectiverôleof the leucocytes is all-important, not only because these cells are capable of digesting venoms owing to their protoplasmic digestive juices, but also because they constitute if not the only, at any rate the principal source of theantitoxic substancesoramboceptors.
Several physiologists, among whom it is right to mention Fontana,69Leydig,70Reichel,71Raphael Blanchard,72Phisalix and Bertrand,73and S. Jourdain,74have pointed out the presence of poison-glands inTropidonotus natrixor other non-venomous snakes, and have explained the immunity enjoyed by these animals with regard to venom as being due to the existence of an internal secretion of this poison.
We also know, from the writings of Phisalix and Bertrand, that the blood of the viper, and that of the salamander and toad are toxic. For my part I have found75that the blood ofNaja,Bungarus,Lachesis, andCerastespossesses the same properties, and a comparative study has been made by Wehrmann,76in my laboratory, of the toxicity of the blood of the viper and of that of the blood of the eel, already established by Mosso (of Turin).77
It is remarkable to find that the blood of the various venomous or non-venomous snakes, like that of certain fishes, such as eels, produces, when injected beneath the skin or into the peritoneum, local and general effects very similar to those of venoms. Injections of 0·5 c.c. to 1 c.c. of the blood of the viper or of the commonsnake, beneath the skin of the guinea-pig, provoke an intense local reaction, which always results in the formation of an eschar. The injection of slightly stronger doses, 1 c.c. to 2 c.c., into the peritoneum, almost always kills these animals, like venom, with symptoms of respiratory asphyxia.
The blood ofNaja tripudians, injected subcutaneously, is lethal to the mouse in a dose of 0·25 c.c.
When this blood is heated, after having been suitably diluted with three or four parts of distilled water, in order to prevent it from coagulating, it is found that a temperature of 70° C. maintained for fifteen minutes is sufficient to cause it to lose all toxic effect. The same applies to the blood of the other poisonous or non-poisonous snakes, and to that of theMurænidæ.
Now, since the majority of venoms resist even prolonged heating at this temperature, it cannot be supposed that the toxicity of the blood is due to its containing venom derived from the internal secretion of the poison-glands, as was thought by Phisalix and Bertrand. On the contrary, it is probable that the toxicity results from the fact that the blood contains diastasic substances of cellular origin, which themselves represent certain of the constituent elements of venoms.
These substances, moreover, possess some of the properties of venoms, as, for instance, the faculty of producing hæmorrhages and of being influenced by antivenomous serum, which causes them to lose a large portion of their toxic qualities.
I have found that they can even be utilised to vaccinate animals against venom; by injecting weak, non-lethal, and repeated doses of diluteCobra-blood into guinea-pigs and rabbits, I have succeeded in rendering them immune to doses ofCobra-venom several times greater than the lethal dose.
There is no doubt that it is to these substances that the poisonous and non-poisonous snakes owe the partial immunity that they themselves enjoy with respect to venoms. We know, in fact, that common snakes suffer without danger many bites fromvipers (Phisalix and Bertrand78), and that theCobrais relatively little affected by inoculation with its own venom or with that of otherColubridæ, such asBungarus, or even ofViperidæ, such asVipera russellii.
This immunity, however, is far from being absolute; I have killed common snakes (Tropidonotus natrix) with doses ofviper-venom ten times greater than the lethal one for the rabbit, andLachesis lanceolatus(from Martinique) with 0·02 gramme of the venom ofNaja tripudians.
Phisalix,79on his part, has shown that, while it was necessary to inject from 100 to 200 milligrammes ofviper-venom into other vipers or common snakes, beneath the skin or into the peritoneum, in order to cause death, the introduction of only 2 to 4 milligrammes of this venom into the brains of these reptiles was sufficient to kill them with the same symptoms of intoxication. This dose, however, is only twenty-five to thirty times greater than the lethal one for the guinea-pig.
The practical lesson to be learnt from the establishment of the foregoing facts is that poisonous snakes of different species must never be placed in the same cage, for these animals sometimes bite each other, and may thus kill one another.
Simon Flexner and Noguchi80have studied the action of the serums ofCrotalus,Ancistrodon, and a non-poisonous species, the pine snake (Pituophis catenifer), on the venoms ofNaja,Ancistrodon, andCrotalus. They found that the serum ofCrotalusrapidly dissolves the red corpuscles of man, the dog, rabbit, guinea-pig, sheep, rat, pigeon, and horse.
The serum of the pine snake affects the same red corpuscles, but in a lesser degree. Heating to 58° C. suppresses the hæmolytic power of these serums, but they can be restored to activity by the addition of a very small quantity of the same serum in a freshcondition, of fresh serum derived from other snakes, or of fresh serum from the guinea-pig.
Antivenomous serum also, when added in a suitable dose, entirely suppresses the hæmolytic action of snake-serums; it has, however, greater effect upon the hæmolysin ofCobra-blood than upon that of the blood of other snakes. This observation had previously been made by W. Stephens,81and it has been verified by Noc in my laboratory.
Crotalus-serum dissolves the red corpuscles of the mongoose (Herpestes ichneumon) of Jamaica, whose extraordinary resistance to venom is well known. But if variable doses ofAncistrodon-venom andCrotalus-serum be made to act simultaneously upon these corpuscles, the latter are no longer dissolved. Again, if, instead of red corpuscles which are but little sensitive, like those of the mongoose, we employ the highly sensitive corpuscles of the guinea-pig, the result is the same. These experiments are regarded by Flexner and Noguchi as proving that the amboceptors of the toxic serum become fixed, in conformity with Ehrlich’s theory of the lateral chains, upon the receptors of the sensitive erythrocytes, and leave no more receptors free for the fixation of the venom.
The same investigators have endeavoured to determine the respective toxicity of the tissues of the different organs ofCrotalus. They found that the most toxic organs are the spleen and the liver; the toxicity of the spinal cord, kidney and muscles is much less. It appears that this toxicity is intimately connected with the quantity of blood that the tissues retain, for the physiological effects observed are identical with those that follow the injection of blood or serum alone.
They also ascertained that the contents of the eggs ofCrotalusare especially rich in poison, and this poison appears to consist for the most part ofneurotoxin, since it does not cause hæmorrhages. Phisalix has observed that the ovules of the viper exhibit analogous toxicity.82
Summing up what has been stated above, we find that the blood of both poisonous and non-poisonous snakes contains toxic substances, destructible by heating to 68° C., and physiologically distinct from venoms, but like the latter possessing the property of dissolving the red corpuscles of the majority of vertebrates and of producing hæmorrhages.
It was long ago pointed out that certain warm-blooded animals, including the mongoose (Herpestes ichneumon, FamilyViverridæ), hedgehog (Erinaceus europæus, FamilyErinaceidæ), pig (Sus scrofa, FamilySuidæ), and some herons (Ajaja, SubfamilyPlataleinæ;Cancroma, SubfamilyCancrominæ;Botaurus, SubfamilyArdeinæ;Mycteria, SubfamilyCiconiinæ), known in Colombia under the namesCulebreroandGuacabo, exhibit a natural immunity with respect to snake-bites.
Pigs devour vipers with great readiness, and in the region of North America which adjoins the Mississippi and its tributaries they are even trained to destroy the young rattle-snakes and other poisonous serpents with which the valleys of these watercourses are infested.
During my stay in Indo-China I inoculated a young pig, beneath the skin of the back, with a dose ofCobra-venom (10 milligrammes) capable of killing a large-sized dog. The animal withstood the injection, but I am inclined to think that this is not a case of true immunity; it is probable that the pig owes its resistance to venom to the fact that its skin is lined with an enormous layer of adipose tissue, which is but very slightly vascular, and in which absorption takes place very slowly. This opinion is corroborated by my discovery that the serum of this animal is entirely destitute of any antitoxic substance. I mixed a dose ofCobra-venom, lethal for the rabbit, with 3·5 and 8 c.c. of pig-serum. These mixtures killed rabbits in the same time as the controls that received the venomdiluted with equal quantities of rabbit-serum or physiological saline solution.
The natural immunity of the mongoose and the hedgehog rests upon more scientifically established facts.
My own experiments upon the immunity of the mongoose were made with six specimens of these little carnivores captured in Guadeloupe (French West Indies), an island in which no poisonous snakes exist; consequently their immunity could not have arisen from their having become accustomed to the bites of venomous reptiles.
I first introduced a mongoose into a cage containing aNaja bungarus(Ophiophagus) of large size. The snake rose up immediately, dilated its hood, and struck savagely at the little animal, which, darting nimbly out of the way, escaped being seized and, frightened for a moment, took refuge in a corner of the cage. Its stupor, however, was but of brief duration, for at the very moment when the hamadryad was preparing to strike at it again, the mongoose, with open mouth and snarling, sprang upon the reptile’s head, bit it hard in the upper jaw and crushed its skull in a few seconds. This scene is in every respect reminiscent of the admirable description given by Rudyard Kipling, in his celebrated “Jungle Book,” of the great war thatRikki-tikki(the Mongoose) fought with Nag (the Cobra) “through the bathrooms of the big bungalow in Segowlee cantonment”:—
“Nag was asleep, and Rikki-tikki looked at his big back, wondering which would be the best place for a good hold. ‘If I don’t break his back at the first jump,’ said Rikki, ‘he can still fight; and if he fights—O Rikki!’ He looked at the thickness of the neck below the hood, but that was too much for him; and a bite near the tail would only make Nag savage.
“’It must be the head,’ he said at last; ‘the head above the hood; and when I am once there, I must not let go.’
“Then he jumped. The head was lying a little clear of the water-jar, under the curve of it; and, as his teeth met, Rikki bracedhis back against the bulge of the red earthenware to hold down the head. This gave him just one second’s purchase, and he made the most of it. Then he was battered to and fro as a rat is shaken by a dog—to and fro on the floor, up and down, and round in great circles; but his eyes were red, and he held on as the body cart-whipped over the floor, upsetting the tin dipper and the soap-dish and the flesh-brush, and banged against the tin side of the bath. As he held he closed his jaws tighter and tighter, for he made sure he would be banged to death, and, for the honour of his family, he preferred to be found with his teeth locked. He was dizzy, aching, and felt shaken to pieces, when something went off like a thunderclap just behind him; a hot wind knocked him senseless, and red fire singed his fur. The big man had been wakened by the noise, and had fired both barrels of a shot-gun into Nag just behind the hood.”83
From the experimental point of view, these stirring battles between mongooses and cobras only show that a mongoose of the size of a large squirrel makes a plucky and victorious attack upon a venomous reptile of the most dangerous species and of very large dimensions; but it is impossible to tell with certainty whether the mongoose has been bitten.
I therefore inoculated a second mongoose with 2 milligrammes of venom, a lethal dose for 4 kilogrammes of rabbit. The animal did not experience the slightest malaise.
I then took blood from three other mongooses, by tying a carotid without killing the animals. This blood, mixed with venom or injected as a prophylactic into rabbits, exhibited an antitoxic power, which, though evident, was of little intensity, and insufficient in all cases as a certain preventative of death. All the rabbits that received a preventive dose varying from 2 to 7 c.c. of mongoose-serum succumbed to inoculation with venom, but with a considerable retardation (from two to five hours) as compared with the controls.
I endeavoured to determine the limit of tolerance of the mongoose with respect to venom. Two of these animals, which had never been inoculated, received doses of venom respectively four times and six times lethal for the rabbit. The first mongoose remained perfectly well; the second was ill for two days, and then recovered. A third mongoose, into which I injected a dose eight times lethal for the rabbit, succumbed in twelve hours.
Fig. 89.—Mongoose seized by a Cobra.(For this illustration I am indebted to the kindness of M. Claine, late French Consul at Rangoon.)
Fig. 89.—Mongoose seized by a Cobra.(For this illustration I am indebted to the kindness of M. Claine, late French Consul at Rangoon.)
It must be concluded from these facts that the West Indian mongoose is but little sensitive to venom; that it is capable of withstanding, without malaise, doses which are considerable in proportion to its size, but that its immunity is far from being absolute. If it is generally the victor in its combats with poisonous snakes, the result is mainly due to the extreme agility with which it is endowed.
A number of experiments have been made by Lewin,84and by Phisalix and Bertrand,85upon the immunity of the hedgehog to the venom ofVipera berus.
It had long been known that hedgehogs are inveterate hunters of vipers, which they devour with avidity. Thanks to the long and sharp spines by which their bodies are protected, they avoid being bitten and contrive to catch the reptiles very cleverly, but it occasionally happens that they do not escape being struck. However, even in these cases they rarely succumb.
Inoculation with fairly large quantities of venom does not make them ill: the dose ofviper-venom lethal for these small animals is about forty times greater than that which kills the guinea-pig. Their power of resistance is therefore beyond doubt.
It may be asked whether this is due to their blood normally containing antitoxic substances. In order to elucidate this question, Phisalix and Bertrand first proved that the blood of normal hedgehogs is toxic to laboratory animals, especially to the guinea-pig. A mixture of this blood with viper-venom cannot therefore be harmless. But it sufficed to heat hedgehog blood to 58° C. to cause it to lose its toxicity, and it was found that it then became antitoxic. Guinea-pigs inoculated in the peritoneum with 8 c.c. of heated hedgehog-serum were able to withstand, immediately afterwards, twice the lethal dose of viper-venom.
It really seems, therefore, that the resistance of the hedgehog to venom is due to the presence of antitoxic substances in its blood. But, as in the case of the mongoose, there is no question here of genuineimmunity.
The same is probably true with respect to the herons of Colombia, theCulebreroandGuacabo, which eagerly search afteryoung snakes for food. No investigations, however, have yet been made upon this subject.
These birds, moreover, are few in number; hunters pursue them for the sake of their brilliantly coloured plumage, and it is to be regretted that no attempt is made to prevent their destruction or to acclimatise them in countries in which poisonous snakes constitute a veritable calamity, such as Martinique, St. Lucia, or India.
In all the countries of the globe where poisonous snakes are formidable to man, there are certain individuals who profess to be secure from all ill-effects from the bites of these reptiles, whether because they are immune to venom, or because they possess secrets which enable them to cure themselves when they happen to have been bitten. Not unnaturally these secrets are sometimes turned to profitable account, and the possessors of them generally enjoy considerable popular influence, and are very highly venerated. Intimate relations with the divinities are freely attributed to them.
Among the Romans the jugglers who carried on the profession of snake-charmers and healers of snake-bites were known asPsylli. Plutarch tells us that Cato, who loved not doctors because they were Greeks, attached a certain number of them to the army of Libya. They were accustomed to expose their children to serpents as soon as they were born, and the mothers, if they had failed in conjugal fidelity, were infallibly punished by the death of their offspring. If, on the contrary, the children were lawful, they had nothing to fear from the bites of the reptiles. “Recens etiam editos serpentibus offerebant; si essent partus adulteri, matrum crimina plectabantur interitu parvulorum; si pudici, probos ortus a morte paterni privilegium tuebatur” (Solinus).
The Libyian Psylli of antiquity still have their representatives in Tunis and in Egypt. Clot Bey writes as follows with reference to the Egyptian Psylli:—
“TheOphiogeni, or Snake-charmers, have been renowned fromall time. Strabo speaks of them, and Prosper Alpinus was a witness of the singular effects of their art. The majority of modern travellers who have visited Egypt have been equally struck with the freedom with which they handle poisonous reptiles and animals.
“The Psylli go from house to house, calling forth and charming the snakes that they may happen to contain. They claim to attract them by means of a particular power. Armed with a short wand, they enter the chamber to be purged from these venomous guests, make a smacking noise with their tongue, spit upon the ground, and pronounce the following incantation: ‘I adjure you, by God, if you are without or within, to appear;I adjure you, by the greatest of names; if you are obedient, appear!If you disobey, die! die!’ The snake, submissive to this command, departs forthwith, issuing from a crack in the wall or floor.”86
India is pre-eminently the country of snake-charmers. There exists an entire caste of Hindus, calledMal, who are professional catchers and vendors of snakes, but do not perform tricks with them.
The snake-charmers are recruited from among another caste, that of theSangisorTubriwallahsof Bengal.
These men, who are usually clothed in yellow robes and wear large turbans, manage the Cobra with really marvellous skill. All travellers who have had the opportunity of crossing India or of touching at a port on the coast or on that of Ceylon have witnessed scenes similar to that described by Natalis Rondot (figs. 90 and 91):—
“Towards six o’clock in the evening a Hindu juggler comes on board. He is poorly clad, and wears a turban decorated with three feathers, and several necklaces of those amulet-sachets calledgris-grisin Senegal. In a flat basket he carries a spectacled Cobra-di-Capello.
Fig. 90.—Indian Snake-charmer at Colombo (Ceylon).
Fig. 90.—Indian Snake-charmer at Colombo (Ceylon).
Fig. 91.—Indian Snake-charmer at Colombo (Ceylon).
Fig. 91.—Indian Snake-charmer at Colombo (Ceylon).
“This man instals himself on deck; we sit down on the seat provided for the officer of the watch, and the sailors form a circle. The basket is placed on the deck and uncovered; the Cobra is coiled up at the bottom of it. The juggler squats a few paces off and commences to play a slow, plaintive, and monotonous air, with a kind of small clarinet (fig. 92), the sounds of which recall those of the Bretonbiniou.
Fig. 92.—Musical Instrument used by Indian Snake-charmers to Charm Cobras.(For this figure I am indebted to the kindness of Dr. Pineau.)
Fig. 92.—Musical Instrument used by Indian Snake-charmers to Charm Cobras.(For this figure I am indebted to the kindness of Dr. Pineau.)
“By degrees the snake moves, extends itself, and then assumes an erect posture, but without quitting the basket. It begins to appear uneasy and endeavours to recognise its surroundings; it becomes agitated and irritated, expands and spreads out its hood, breathes hard rather than hisses, and frequently and quickly shoots out its slender forked tongue; several times it makes a violent dart as though to attack the juggler; it frequently trembles, or rather gives sudden starts. The juggler keeps his eyes always fastened upon the snake, and gazes at it with a singular fixed stare. After some time, about ten or twelve minutes, the Cobra becomes less animated, grows quiet, and then sways as though influenced by the slow and monotonous rhythm of the musician; it keeps incessantly darting out its tongue. Little by little it is brought toa sort of somnolent condition. Its eyes, which at first watched the juggler as though in order to take him by surprise, are, to a certain extent, fixed and fascinated by the latter’s gaze. The Hindu takes advantage of this moment of stupefaction on the part of the snake by approaching it slowly without ceasing to play, and touches the head of the Cobra, first with his nose and then with his tongue. Although this takes but an instant the reptile starts out of its sleep, and the juggler has barely time to throw himself backwards so as not to be struck by the snake, which makes a furious dart at him.
“We doubt whether the Cobra still has it fangs, and whether the Hindu incurs any real danger in approaching it. Accordingly we promise our man a Spanish piastre if he will make the snake bite a couple of fowls. A black hen, which struggles violently, is taken and offered to the Cobra, which half rises, looks at the bird, bites it, and lets it go. The fowl is released and runs off terrified. Six-minutes later, by the watch, it vomits, stretches out its legs, and dies. A second fowl is placed in front of the snake, which bites it twice, and the bird dies in eight minutes.”87
Certain jugglers exhibit snakes from which they have taken care to extract the fangs; they offer the animal a piece of cloth or soft stuff into which it drives its poison-teeth, and the fabric is then quickly snatched away in order by this means to break off the poison-fangs that have penetrated it. This operation is repeated at certain intervals with a view to preventing the reserve fangs from coming into use, and the reptiles can then be handled without any danger.
It is unquestionable, however, and I have personally satisfied myself of the fact, that many genuine snake-charmers go through their performances with Cobras whose poison-apparatus is absolutely intact. That they almost always avoid being bitten is due to a perfect knowledge of the habits and movements of these reptiles.Nevertheless, accidents sometimes happen to them, and every year a few of them succumb in pursuit of their calling (see p. 370). Still, it may be asserted that some of them really know how to vaccinate themselves against venom, by making young Cobras bite them from time to time.
It is stated by E. C. Cotes,88formerly of the Calcutta Museum, that the Indian snake-charmers do not extract the poison-fangs from their snakes. Even though deprived of its fangs, the snake would still be dangerous on account of its other teeth, the punctures of which would provide another channel for the penetration of the venom.
Snake-charmers pretend that they owe their immunity to graduated inoculations. This is not yet conclusively proved; what is better established is that they take the greatest care to avoid being bitten, and that in so doing they display the most remarkable skill.
Even in France we are acquainted with professional viper-catchers, who employ the method of graduated inoculations in order to render themselves immune to the bites of indigenous reptiles. One of these men, who lives near Arbois (Jura), takes good care to get himself bitten, at least once a year, by a young viper; when he forgets this precaution and happens to be bitten, he always feels the effects much more severely.
Fraser89(of Edinburgh) thinks that the repeated ingestion of small quantities of venom may suffice to confer immunity, and he mentions a certain number of experiments performed by him upon white rats and kittens, from which it would appear that the ingestion of venom, continued for a long time, finally renders these animals absolutely refractory to subcutaneous inoculation with doses of the same venom several times greater than the lethal one. He therefore concludes that this process of vaccination may probably be in use among snake-charmers.
I have submitted this hypothesis to the test of experiment. I succeeded in makingadultrabbits, guinea-pigs, and pigeons absorb enormous doses ofCobra-venom by way of the alimentary canal. In this manner I have administered doses as much as a thousand times greater than the lethal one, yet I have never been able to prove that the serum of these animals became antitoxic.
On the other hand, I have succeeded in vaccinating very young guinea-pigs and young rabbits which were still being suckled, by making them absorb, every second day, minimal and certainly innocuous doses of very dilute venom. In the case of young animals, venom is not modified by the digestive juices, and a portion of it is absorbed by the mucous membrane of the intestine. When the dose ingested is suitably reduced they withstand it, and when these ingestions are repeated every second or third day during the first weeks of life, the animals become perfectly vaccinated against doses certainly lethal for controls of the same age and weight. But it is always difficult to push the vaccination far enough for the serum to acquire antitoxic properties, and I have never been able to prove the appearance of the latter.
I think, however, that it ought to be possible to arrive at this result by experimenting upon animals such as lambs, kids, calves, or foals, the intestine of which remains permeable to toxins for a sufficiently long period.
It may be that certain snake-charmers, who claim to possess family secrets which they transmit from father to son, employ an analogous method in order, in their infancy, to confer immunity to venoms upon those of their male children who are to inherit their strange and lucrative profession.
In Mexico, certain Indians calledCurados de Culebrasknow how to acquire the privilege of being able to be bitten by poisonous snakes without the least danger to life, by inoculating themselves several times with the teeth of rattle-snakes.
Dr. Jacolot,90a naval surgeon, while staying at Tuxpan, madeenquiries as to theseCurados de Culebras, and was able to satisfy himself that their immunity is an actual fact.
The process of vaccination employed by the natives of Tuxpan is as follows:—A preparatory treatment is necessary. On the very day on which a man is to inoculate himself or get himself inoculated, he takes from 5 to 15 tubers of a plant known by the name ofMano de Sapo(i.e., Toad’s hand,Dorstenia contrayerva, FamilyUrticaceæ). These tubers must—and this is absolutely necessary—be administered on aFriday, and always in an odd number, 5, 7, 9, &c., up to 15, according to the tolerance of the subject.
If the plant be gathered on the first Friday in March it possesses its marvellous properties in the highest degree; in this case, even if it be dry, it is still excellent for the preparatory stage of the inoculation.
The physiological effects ofmano de sapoare not very marked: the circulation is slightly diminished and a sensation of cold is experienced, but there are no nervous troubles. The subject frequently has attacks of vomiting or nausea. The inclination to vomit must be fought against, for if the plant should happen to be rejected it would be dangerous to submit to the inoculation.
The root of themano de sapois usually taken fresh. There is another indispensable precaution: while undergoing this treatment it is necessary to abstain from all sexual intercourse for three days after the first inoculation, for two days after the second, and for one day after the third.
For the inoculation a large snake’s tooth, that is to say, one of the fangs, is employed, and the fangs of the most poisonous snakes, such as the rattle-snake (cuatro narices), are selected. The snake must be killed on aFriday, and the fangs extracted the same day. The same fang may serve for several years!
The inoculation is commenced on the dorsal surface of the left foot; care must be taken to avoid coming into contact with a vein. The skin is torn with the point of the fang, so that it bleeds a little, and the incision is in the shape of a square.
From the left foot the operator passes to the right wrist (anterior surface), then to the right foot (dorsal surface), and left wrist (anterior surface), always changing from one side of the body to the other.
Operations are continued on the left thigh, then on the right arm, right thigh, and left arm; in this way all the limbs are inoculated. On the body an inoculation is made in the centre of the sternum; another is made in the nape, and a final one in the centre of the forehead. The finishing touch is given with the semblance of a square incision in the tongue.
At least seven series of similar inoculations are necessary to protect a man from the spells of the serpent, and at the same time to confer upon him the faculty of curing by suction the bites of the venomous snakes that are most dreaded.
During the whole of the period in which the Indian thus submits to successive inoculations, his health shows no noteworthy derangement. He feels a slight headache and a strange inclination towards alcoholic drinks. But when the moon is at the full, then indeed, an excitement which is dangerous in another way takes possession of him. His cerebral faculties become over-excited, and he feels that his senses are deserting him; his eyes become bloodshot, and he is pursued and tormented by an irresistible impulse to bite. He has itching sensations in his gums, his mouth burns, and salivation is greatly increased. He feels that he is going to give way to the necessity to bite, and then he flees to the woods, where he bites the trees viciously, tears their bark and discharges his venom. His poisonous saliva mingles with the sap, and, surprising phenomenon, the tree withers and dies!
Woe to the man or animal who happens to be bitten by aCurado de Culebrain a fit of passion. The victim will die as quickly as if he had been bitten by a snake!
Almost all the semi-savage people of Guiana, and of the valleys of the Orinoco and the Amazons, as also the tribes of Central Africa and the races of India, possess witch-doctors, who pretendto be in possession of means to preserve themselves from snake-bites, which are just as ridiculous and infallible as the procedure described above.
The archives of a criminal anthropology contain the story of a Lyonnese gold-seeker, who had himself immunised against venom by an aboriginal native of Guiana:91—
“The Indian took, from a bottle which contained several of them, a tooth of theGrage(Lachesis atrox), an extremely poisonous snake, and with it made upon my instep three incisions about 3 centimetres in breadth. He allowed the wounds to bleed for a minute. I then experienced a fainting sensation, and large drops of sweat rolled from my forehead. The wounds were next rubbed with a blackish powder. I have since learnt that this powder was composed of the liver and gall of the animal, dried in the sun and pounded up with the poison-glands. The blood immediately ceased to flow. The Indian chewed some leaves of a tree mixed with this powder, and, applying his lips to the sore, injected into it as much saliva as he could, making an effort as though to inflate a balloon. This completed the operation.
“Since then I have been bitten seven times by different species of very dangerous snakes, such as theGrage, coral-snake, &c., and have never even had an attack of fever. The Galibi, Boni, and Emerillon Indians, the Bosse negroes, and all the aboriginal natives of Guiana employ the same method of procedure. They even pretend that this kind of vaccination is transmissible to their offspring, and that the hereditary immunity is maintained through several generations.”
Some years ago Mons. d’Abbadie communicated to the Académie des Sciences92a note from Colonel Serpa Pinto relating to another method of vaccination employed by the natives of Mozambique, which the Colonel himself consented to undergo.
“I was vaccinated,” writes Colonel Serpa Pinto, “at Inhambane (on the East Coast of Africa), among the Vatuas. These people extract the poison of a snake which is known in Portuguese as theAlcatifa(i.e., carpet), and is so called on account of the variegated colour of its skin, which resembles a carpet. I am not acquainted with the means employed in order to obtain the poison, which is mixed with vegetable substances, and forms with the latter a dark brown viscid paste.
“Two parallel incisions, 5 millimetres in length, are made in the skin, and into these is introduced the paste containing the poison. These incisions are made on the arms, near the junction of the radius and ulna with the carpal bones, on the back of the hand, on the back, on the shoulder-blades, and on the feet, near the great toes. After the operation the natives exact an oath that the vaccinated one will never kill a poisonous snake, because they say that henceforth the snake is his intimate friend, and they throw upon him an Alcatifa snake, which does not bite him.
“After undergoing this operation my whole body was swollen up for a week, and I underwent every possible kind of suffering.
“I have never been bitten by any snake, and cannot vouch for the infallibility of this remedy. The Vatuas do so, however, and they never kill a snake.
“A short time after having been vaccinated, I was stung, when in the Seychelle Islands, by a scorpion, which did me no harm. Ten years later, at the time of my journey across Africa, I was stung by another scorpion which hurt me dreadfully, and for a week I thought that I was going to die or lose my arm.”
Mystification and superstitious ideas play, as we see, a very great part in this preventive treatment, which is undergone by the natives of certain countries and snake-catchers or charmers. But it is not very surprising that, thanks to successive and repeated inoculations, a man can succeed in acquiring sufficient immunity to preserve himself from snake-bites.
In ancient times it was even pretended that it was possible forthis immunity to be transmitted in certain cases by heredity, and thus we can understand how the profession of snake-charmer was hereditary in certain native families in India or Egypt.
With reference to this subject, Professor Landouzy, in his fine work on serum therapeutics, quotes a passage from “The Pharsalia” of Lucan describing, in the year 60A.D., the customs of the Psylli, a people encountered by the army of Cato during its sojourn in Africa. This passage is so interesting that I cannot refrain from reproducing it:—