As showing what kind of trouble the “poison-ivy” and “poison-oak” (another kind of Rhus or Sumach) give in the United States, I will quote a letter I have received from an American lady well known in London society. She says: “I have known, suffered, and struggled against the poison-ivy in America from my earliest years, when my poor mother lay for days with blinded and swollen eyes, having gathered it inadvertently. The ‘poison-ivy,’ as we call it, is a curse to country life, outside the purely artificial and cultivated gardens, and even there it creeps in insidiously.” She describes a beautiful farm property on Lake Champlain, on the Canadian border, where she and her family would spend many weeks in summer in order to enjoy the delights of complete seclusion in wild, unspoilt country: “The one and only drawback to the place was,” she writes, “the inexhaustible quantity of poison-ivy. Our first duty had been to teach my two daughters and their governess how to distinguish and avoid contact with it. The one and only rule was that the poison-ivy has the clusters of three leaflets (the middle leaflet with a longer stalk, E.R.L.), whereas the woodbine (not the English woodbine, which is a convolvulus, E.R.L.), or, as you call it, ‘Virginian creeper,’ has five leaflets in a cluster. Every path which we used frequently and necessarily, such as the path to the boat-house, and to the cove where the bathing-house stood, we kept cleared of the Rhus for a sufficient width, but in the woods eternal vigilance was the price of safety. To uproot and burn is the only way to destroy it, but, of course, that involves danger to the one who does the work, because contact with the spade used, and with the garments which touched the ivy, might communicate the poison. The farmer and the countryfolk about declared that the fumes from the burning plant could and did poison those who breathed them. We used to turn a flock of sheep into the most used parts. They prefer the poison-ivy to grass, and greedily eat down every leaf within reach in hedge or path. But that, of course, was a mere temporary safety, as the plant is most tenacious of life. I personally had a most grievous experience one summer. I can only suppose that my dress, though very short for wood and hill walking, brushed over the poisonous plant, and then, when I undressed, came into contact with my skin. Both legs became covered with the eruption, eventually developing pustules, and the agony of itching, burning, and smarting was indescribable. The first remedy applied is usually a frequent use of baths of some alkali, generally common soda. With me it was altogether inadequate, and the doctor carefully covered the affected parts with a thick layer of bismuth, and bandaged them, so as to exclude all air. But it took weeks to cure me. A very serious result in many cases is that there is a recurrence of the itching for several years.”
[XII]
POISONS AND STINGS OF PLANTS AND ANIMALS
To give an account of poisonous plants would require a whole volume. Among plants of every degree and kind are many which produce special chemical substances which are more or less poisonous, and yet often of the greatest value to man when used in appropriate doses, though injurious and even deadly if swallowed in large quantity. Plants are laboratories which build up in a thousand varieties wonderful chemical bodies, some crystalline, some oils, some volatile (as perfumes and aromatic substances), some brilliantly coloured (used as dyes), some pungent, some antiseptic, some of the greatest value as food, and some even digestive, similar to or identical with those formed in the stomach of an animal.
Man, the chemist, every year is learning how to produce in his own laboratories, from coal and wood refuse, many of these bodies, so as to become to an ever-increasing extent independent of the somewhat capricious and costly services of the chemists supplied by nature—the plants. In a recent exhibition there was a case showing on one side the various essential oils used to make up a flask of eau-de-Cologne, and specimens of the plants, flowers, leaves, and fruits from which they are distilled. On the other side of the case was a series of bottles showing the steps in the process by which the modern chemist manufactures from coal-tar and coker-butter the same bodies which give value to the vegetable extracts, and there was finally a bottle of what is called “synthetic eau-de-Cologne”—that is, eau-de-Cologne put together from the products manufactured by the human, instead of the vegetable, chemist.
Whilst man has learnt to avoid swallowing poisonous plants, although occasionally blundering over pretty-looking berries and deceptive mushrooms, he has had little to fear in that way from animals. To a small degree this is due to the fact that only parts of animals are eaten by man, and those very generally are cooked before being eaten, the heating often sufficing to destroy substances present in flesh, fish, and fowl which would be poisonous if taken raw. But, as a matter of fact, animals do not generally protect themselves from being eaten, as plants largely do, by developing nasty or poisonous substances in their flesh, though some do. They fight rather by claws, teeth, and poison glands therewith connected, or else escape by extra quick locomotion, a method not possible to plants. Many insects (butterflies, beetles, and bugs), however, produce nasty aromatic substances which cause animals like birds and lizards to reject them as food. The toad and the salamander both produce a very deadly poison in their damp, soft skins, which causes any animal to drop them from its mouth, and to regret “bitterly” the attempt to swallow them. The frog has no such poison in its skin, but can jump out of harm’s way. The strong yellow and black marking of the European salamander is what is called a “warning” coloration, just as is the yellow and black outfit of the poisonous wasp. Animals learn to leave the yellow and black livery untouched, and the creatures so marked escape the injury which would be caused them by tentative bites.
There is a curious variation as to susceptibility on the part of man to poison in the flesh of fishes and shell-fishes when taken by him as food. The word “idiosyncrasy” is applied to such individual susceptibility, and is, of course, applicable to the susceptibility shown by some persons to the poison of the American poison-vine, described in the last article, and of others to acute inflammation from the dust of hayfields. Some persons cannot eat lobster, crab, or oysters or mussels without being poisoned in a varying degree by certain substances present in those “shell-fish” even when cooked. Often a “rash” is caused on the skin, and colic. Others, again, cannot eat any fish of any kind without being poisoned in a similar way, or possibly are only liable to be poisoned by grey mullet or by mackerel. The most curious cases of this individual variability are found in the rash and fever caused by the vegetable drug quinine in rare instances, and the violent excitement produced in some persons by the usually soporific laudanum. All such cases have very great interest as showing us what a small difference separates an agreeable flavour or a valuable medicine from a rank poison, and how readily the chemical susceptibility of a complex organism like man may vary between toleration and deathly response, without any concomitant indication of such difference being apparent (in our present state of knowledge), in two individuals, to one of whom that is poison which to the other is meat. They also furnish a parallel to that marvellous conversion of “toxin” into “anti-toxin,” in consequence of which the blood of an animal injected with small, increasing doses of deadly snake poison or diphtheria poison becomes an antidote to the same poison taken into the blood of an unprepared animal.
There is, over and above these special cases of fish foods which are tolerated by some and are poison to others, a whole series of fishes which cannot be eaten by any one without serious poisoning being the result, even when the fish are carefully cooked. Happily, these fishes are rarely, if ever, caught on our own coasts. They produce, when even small bits are eaten, violent irritation of the intestine, and death, the symptoms resembling in many respects those of cholera. The curious bright-coloured, beaked fish of tropical seas and coral reefs, with two or four large front teeth and spherical spine-covered bodies, and the trigger fish of the same regions, are the chief of these poisonous fish. But there is a true anchovy on the coast of Japan, and a small herring in the West Indies, and a goby on the Indian coast (Pondicherry), all of which are deadly poison even when cooked; and there are many others. So one has to be careful about fish-eating in the remoter parts of the world. The poisons of these fish with poisonous flesh have not been carefully studied, but they seem to resemble chemically the poisons produced by certain putrefactive microbes.