There are very few plants which have a power of diffusing poison around them; usually it is necessary to touch or to eat portions of a plant before it can exert any poisonous effect. The eighteenth-century story of the upas-tree of Java, which was fabled to fill a whole valley with its poisonous emanation, and to cause the death of animals and birds at a distance of fifteen miles, is now known to be a romantic invention. The tree in question is merely one having a poisonous juice which was extracted and used by the wilder races of Java as an arrow poison. It is stated that one of the stinging-nettles of tropical India has such virulent poison and such an abundance of it in the hairs on its surface, that explorers have been injured by merely approaching it, the detached hairs probably floating in the air and getting into the eyes, nose, and throat of any one coming near it. The poison of the poisonous stings of both plants and of animals has been to some extent examined of late years. It is a curious fact that there are proportionately few plants which sting as compared with the number and variety of animals which do so. On the other hand, there are an enormous number of plants which are poisonous to man when eaten by him, but there are very few animals which are so. It will be of interest to my readers to know that I received, in consequence of the publication of the foregoing account of the “Poison-vine” or “Poison-ivy,” more than fifty letters and boxes containing leaves. At Kew Gardens nearly a hundred applications were made with a request for the identification of leaves. The proportion of cases in which leaves of true poison-ivy (_Rhus toxicodendron_) were sent to me seems to be the same as that which they observed at Kew—only two samples of the leaves sent to me were those of the true poison-ivy. Hence we may conclude that the plant has not been very largely introduced in this country, and probably there are not many hundred cases existing in England of the painful malady which it can, in certain people, produce. I have, however, received information of several instances of this poisoning from different parts of the country, which are either now under treatment or have been cured, and in some cases the poison-ivy has been discovered as the cause, owing to the description which I published. It is certainly true that the illness caused by this plant only attacks a small proportion of those who handle it, and it is possible that the plant is more virulent at some seasons and in some soils than in others. In the United States, even in the neighbourhood of New York, it is a real danger, and is recognised as such, but as appears from a letter which I quote below, the reason of the dread which the “poison-ivy” excites in the States depends on the fact that it is not there a mere garden plant, but grows wild in great abundance in the woodlands frequented by holiday-makers and lovers of natural forest and lakeside wilderness.