XI

A RIVAL OF THE FABLED UPAS TREE

WE

E are so accustomed nowadays to danger to life and health from minute, invisible germs, and to exerting all our skill in order to destroy them, that the knowledge of the existence of large and beautiful trees in our midst which can, and do, cause terrible disease and suffering by their mere presence, comes as a shock, and produces a peculiar sense of insecurity greater even than that excited by unseen micro-organisms. For the trees of which I am about to speak are cultivated in our gardens, trained up against the walls of our houses with loving care, and admired for the beautiful autumn tints of their leaves. Yet it is now certain that they are the cause in many persons of most terrible suffering and illness. I am glad to be able to warn my readers in regard to these plants, and I shall be very much interested to hear whether the information which I am about to give proves to be of value in any particular case.

A married couple, friends of my own, went to live, about fourteen years ago, in a newly built, detached house, standing in its own garden, in the neighbourhood of an English city. After they had been there two years the lady developed a very painful eruption or eczema on the face, which, in the course of a few weeks, caused the eyes, nose, and lips to swell to an extraordinary

degree, accompanied by the formation of blisters and breaking of the skin. The affection spread to the body, and caused constant pain and corresponding prostration. Her medical attendants were unable either to cure or to account for her condition. After some months she left home, and entirely recovered. But every year the same distressing and disfiguring illness attacked her (commencing in the month of June), and disappeared as soon as she left her house, only to return when she came back to it. The doctors spoke of her affliction as a mysterious form of erysipelas, and even suggested blood-poisoning as the cause. For long periods she was so ill and in so much pain that she was unable to see her friends, and her life was at times in danger.

Two years ago a weekly newspaper published an account, written by a correspondent, of an illness from. which he had suffered-exactly agreeing with that which had for so many years tortured my friend's wife. This writer stated that he had ascertained that the disease was due to the action of a poison given off by a creeper which grew on the walls of his house. He had supposed this plant to be a Virginian creeper; but he had discovered that it was in reality the Californian poison-vine called by botanists Rhus toxicodendron. The terribly poisonous nature of this plant is well-known to the people of the United States. It is one of the sumach trees, of which other poisonous kinds are known, whilst more than one species is used (especially in Japan) for preparing a resinous varnish which is used in the manufacture of "lacquered " articles. The writer in the weekly paper stated that he had cut down and burnt the poisonvine which grew on the walls of his house, and that his sufferings had ceased. My friend happened to read this account, and immediately examined his own house. He found a creeper resembling a Virginian creeper, but

having three leaflets or divisions of the leaf instead of five, growing around his drawing-room window, and actually spreading its branches and leaves over the window of his wife's bedroom. He sent specimens of the creeper to Kew, where it was at once identified as the Rhus toxicodendron or American poison-vine or poison-ivy. He caused the plant to be removed and burnt, and, except for a slight attack in July, due no doubt to fragments of the leaves still carried about in the form of dust, his wife has recovered her health.

I have looked into this matter with care, and I find that (presumably in ignorance) nurserymen in England have sold specimens of the poison-vine for planting as creepers, under the name Ampelopsis Hoggii. The smaller-leaved Virginian creeper, with self-attaching tendrils, is known as Ampelopsis Veitchii, and is, like the larger Virginian creeper (A. quinquefoliata), quite harmless. The poison-vine is not an Ampelopsis at all, not even one of the Vitacea or vine family, as that genus is. It is a Sumach or Rhus, and belongs to a distinct family, the Terebinthaceæ. It has a three-split leaf, not five leaflets, as has the large Virginian creeper, nor a small three-pointed leaf, as has the Ampelopsis Veitchii. The Veitchii frequently has the leaf also split into three leaflets, but the stalk of the middle leaflet is not relatively so long as it is in the poison-vine. The differences and resemblances in the leaves of these plants are shown in the accompanying illustration (Fig. 14), which has been prepared from actual specimens for this book.

The people of the United States are on their guard against this plant, knowing its terrible properties. Sir William Thiselton Dyer, formerly director of Kew Gardens, tells me that specimens of the "American poison-vine" are grown in the garden at Kew, and that he has been present when American visitors (ladies) literally screamed with horror on seeing it, and ran from it as from a mad

dog. Several cases are on record of the mysterious poisoning produced by this plant in England; but it is strangely unfamiliar to medical practitioners — indeed, practically unknown to them, although I have ascertained that many English people, especially ladies, have been victims for some years to its unsuspected influence.

At the University of Harvard, in Cambridge, Massachusetts, they have made quite recently a thorough examination of the poison-vine in the laboratory, with the following results: The poison is an oil—a fixed oil, not a volatile one, as we might have imagined from its mysterious action at a distance. The oil exists in all parts of the plant, even in the fine hairs and cuticle of the leaf. It can be extracted by means of ether, and is one of the most virulent irritants known, having a very curious penetrating and persistent action, and producing violent pain and destruction of tissue when placed on the skin in quantity so minute (one-thousandth of a milligram in two drops of olive oil) as to be beyond the terms of everyday language. It seems to be usually brought to the eyes, nose, lips, and skin of the face and body by the fingers which have touched a leaf or fragments of a leaf in powder. The dead leaf in winter still retains the oil, and minute dust-like particles can carry it. The treatment for it is washing with soap, oil, and ether at an early stage of the attack-especial care being taken to free the fingers from any minute traces of the oil adhering to them.

The poison of the poison-vine only acts upon a limited number of individuals, many people being perfectly immune. At the same time, the effect upon susceptible people appears to be enhanced with every fresh attack; even after the total removal of the poison-vine and its dust from proximity to a susceptible person, he or she is apt for some time-owing to the retention of some trace

FIG. 14.-Drawings, about half the natural size, of the leaves of the common quinquefoliate Virginian creeper (1 and 2), of the adherent " Ampelopsis Veitchii" (3 and 4), and of the poison-vine, Rhus toxicodendron (5 and 6). From specimens in the Botanical Department of the Natural History Museum. Note especially the greater length of the stalk of the central leaflet in the poison-vine. Note also that the common Virginian creeper has sometimes only three leaflets (2) instead of five, and that "Veitchii" has either three leaflets, as in 3, or has the leaflets united into one threepointed leaf, as in 4.