Popular Science Monthly/Volume 14/January 1879/Curari or Woorara Poison

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IT is almost three centuries since Sir Walter Raleigh, after the discovery of Guiana, brought to Europe some arrows poisoned with a substance called by him curari. This poison was then in general use among the tribes inhabiting the Atlantic slope of South America. To-day we must penetrate into the depths of the forests to find the remnants of the ancient populations who possess the recipe for preparing curari. It may safely be affirmed that by next century it will have disappeared, either through the annihilation of these races, who are vanishing before the whites, or blending with them by intermarriage, or, above all, because firearms, obtained by way of barter from European traders, are steadily superseding the ancient implements of war and of the chase.

The arrow-poison is usually prepared from a substance often called veneno by the Spanish-Americans, and which occasionally happens to be brought to Europe under the name of curari. This substance, which the natives carry about in little earthenware pots or in calabashes, is a black, solid extract, with glistening fracture, in appearance very much like the black, inspissated juice of licorice. The active principle of curari is soluble in water, alcohol, blood, and all animal fluids; it is mixed with many impurities, which remain suspended in the solution, and among which the microscope detects vegetable débris, cells, and fibres. Ether and spirits of turpentine precipitate the curari poison, and in this way Messrs. Boussingault and Roulin have been able to isolate the active principle of curari, which they call curarin. Its chemical constitution is not yet made out; it is not crystallizable, has the look of horn, is very hygroscopic, and easily soluble in water and in alcohol. The watery solution is not affected by boiling, and appears to preserve its toxic property for an indefinite time, precisely like the dried curari on the tips of arrows, a circumstance which renders these weapons very dangerous objects to handle.

Curari is prepared at long intervals by the natives of South America, whenever the supply, which is divided between the hunters and the warriors, has become exhausted. The mode of preparation differs according to locality, but these differences are not essential. The ingredients are everywhere either the same or at least analogous, for the curaris manufactured in different regions amid the almost unexplored forests of Guiana and Brazil always present the same toxic properties. Sometimes curari is prepared openly and without mystery on some high festival of the tribe, with the usual accompaniment of copious libations of strong drink. And, by-the-way, it has been remarked by Humboldt that during a festival it is a rare thing to find a native that is not intoxicated, drunkenness being unfortunately, in all latitudes, the habitual expression of gladness among the ruder classes of mankind.

At other times the arrow-poison is prepared only by the medicine men, who hedge its preparation around with superstitious practices and mystic ceremonies, designed to enhance their own prestige and influence. The exaggerated reports of travelers have still further complicated the matter, as when we are assured that in the preparation of the curari some old hag of the tribe shuts herself up in a hut with the kettle in which the poisonous ingredients are boiled, and that, if the process is successful, she herself dies by inhaling their noxious emanations. This is a fable, for curari is not volatile.

It has also been stated that, when the curari begins to thicken, the natives throw into the pot ants with venomous stings, and the fangs and poison-glands of the most deadly serpents, such as the rattlesnake. Possibly these accessories may have sometimes been employed, but we now know that they are not essential, and that excellent curaris are prepared solely from vegetal substances. According to Goudot, the tribes living on the New Granada frontier cut down in the woods certain climbing plants of the genus Strychnos, from which exudes at the cuts a quantity of acrid sap. The wood is crushed and macerated in water for forty-eight hours; it is then pressed, and the liquid is carefully filtered. After filtration it is slowly evaporated, till it reaches the required degree of concentration. It is now distributed among a number of little earthenware pots, which are placed on hot embers, and the process of evaporation is carried on with still greater care, till the poison acquires the consistence of a soft paste and is perfectly free from water.

Dr. Jobert is now engaged in studying in their native habitat the properties of the various plants which are known to have been employed in the preparation of curari, and he has had prepared under his own supervision, entirely from vegetal substances, one of the best of American curaris, that of the Tecuna Indians living' on the Calderão, Brazil, near the Peruvian border. Some fine scrapings of Urari uva, a climbing plant of the genus Strychnos, and of the Eko or Pani, of the family Menispermaceæ, also a climber, were steeped in cold water. This liquid was then boiled for six hours, and there were thrown into it fragments of various plants, among them an Aroidea (Taja), and three different species of Piperaceæ. In this way the liquid was made to assume the consistency of mucilage; it was then suffered to cool, and became as thick as shoe-blacking. Dr. Jobert has found by experiment that the Urari and the Taja are the most rapidly fatal in their effects of all the ingredients, and that the Pani, administered by itself, is less rapid.

The Indians use curari to poison their arrows both for hunting and for war. The hunting-arrows, intended to be shot from a bow, have a detachable point; those shot from the sarbacand or blow-gun are very small, and consist of a slender shaft of iron-wood with a very sharp point, which bears the poison. Sometimes the poison is used highly diluted or in very small quantity, so as to produce in the victim simply a numbness, which passes away by degrees, but which in the mean time checks the animal in its course or in its flight, or causes it to fall from the tree in which it may happen to be. It is thus, we are told, that the Indians capture monkeys and parrots for sale to the European traders. Often the animal is killed by the arrow, but nevertheless its flesh may be eaten with impunity, for the very minute dose of the curari which enters the stomach with a mass of food is innocuous. Indeed, we know that curari, like the venom of serpents and the saliva of a rabid dog, may be introduced without injury into the digestive organs, provided the mucous surfaces of the latter are free from all lesion.

Curari has been mixed with the food given to dogs and rabbits in quantity far more than enough to produce fatal poisoning through a wound, and yet the animals have suffered no inconvenience.

Claude Bernard, however, has very clearly shown that this innocuousness of curari when administered through the stomach is relative only. In this respect curari resembles many other substances, both medicines and poisons. The peculiarity of their action is explained by the property which amorphous substances possess of being very slowly absorbed by the mucous membranes. By young mammals and birds while fasting, and while intestinal absorption is very active, curari cannot be taken into the stomach with impunity. We can only say that it takes a much larger quantity of curari to produce poisoning through the digestive organs than through an external wound.

Curari introduced into living tissues produces death all the sooner the more quickly it enters the circulation. Death comes quicker when a solution of curari is injected under the skin than when the dry poison is introduced by the point of an arrow. Vigorous animals with rapid circulation of blood are more easily poisoned than those which are weakly; and with an equal dose of poison and with animals of equal size, those whose temperature is constant die more quickly than those whose temperature is variable (reptiles, batrachians, fishes), and, among the former, birds succumb more quickly than mammals.

The animal at first does not feel the wound, for curari possesses no caustic property. In the case of very small animals death is almost instantaneous. In birds and mammals of a large size, and in all animals of variable temperature, death usually occurs in from five to twelve minutes, if there is an excess of the poison. The animal lies down as though it would sleep, keeping the eyes open, with a placid expression. Soon it is seized with a progressive paralysis of the motor nerves, proceeding from the extremities to the centre. The muscles of respiratory movement are the last to succumb, and the animal dies from asphyxia.

To all appearance, nothing could be calmer than this progressive state of stupor; there is no agitation, no expression of suffering. The mouth remains shut, without foam or saliva. Life seems to be extinguished slowly, like some liquid that gradually flows away. In view of these treacherous symptoms, a member of the Society for the Prevention of Cruelty to Animals might be tempted to urge the use of curari in lieu of the brutal modes at present in vogue for slaughtering old, worn-out horses.

To Claude Bernard science is indebted for the exact determination of the specific action of curari. Vital activity presents a threefold series of distinct and coördinated organic elements, which play the part of excitants of one another. The starting-point of physiological action is the sensitive nerve-element. Its vibration is transmitted along its axis, and on reaching the nerve-cell—a regular relay—the sensory vibration is transformed into a motor vibration. This latter, in turn, is propagated through the motor nerve-element, and on reaching its peripheric extremity causes the fibre of the muscle to vibrate, and this, reacting in virtue of its essential property, produces contraction, and consequently motion.

Now, each of the three elements, sensory, motor, and muscular, lives and dies after a fashion of its own, and there are poisons proper to each. But, inasmuch as vital manifestations require the coöperation of these three activities, if one be suppressed, the other two continue to live indeed, but they no longer mean anything, just as a phrase loses its meaning if one of its members be dropped out. Claude Bernard's experiments have proved that the motor nerve-element alone is affected by curari, and that the other two organic elements of the animal retain their physiological properties. The mind is not destroyed, the muscular fibre still has the power of contraction, and indeed does contract under the influence of electric discharges. Motor power alone is destroyed; if the characteristic manifestations of life have disappeared, it is not because they are really extinguished, but because they have been one after another turned back by the paralyzing action of the poison. In that motionless body, back of that lack-lustre eye, with all these semblances of death, sensibility and mind still persist intact; what looks to be a dead carcass hears and knows all that goes on around it; it feels pain when its body is pinched or burned; it still has feeling and will, but it has lost the instrument needed for manifesting them. The movements which are most expressive are the earliest to disappear—first voice, then the movements of the limbs, those of the face and the thorax, and lastly the movements of the eyes.

Is it possible to conceive a more dreadful torture than that endured by a mind which thus witnesses the privation of its organs one after another, and shut up, as it were, in the fullness of life within a corpse?

  1. Translated from La Nature by J. Fitzgerald, A.M.