The part played by the barbed hairs, those atoms which the least movement of the air disseminates in all directions, is confined to conveying to our face and hands the irritant substance in which they are impregnated. Their barbs hold them in place and thus permit [[144]]the virus to act. It is even probable that, by means of slight scratches which would otherwise pass unnoticed, they assist the action of the stinging fluid.
Shortly after handling the Processionaries, a delicate epidermis becomes tumefied, red and painful. Without being immediate, the action of the caterpillar is prompt. The extract made with ether, on the other hand, causes pain and rubefaction only after a longish interval. What does it need to produce more rapid ulceration? To all appearances, the action of the hairs.
The direct stinging caused by the caterpillar is nothing like so serious as that produced by the ethereal extract concentrated in a few drops. Never before, in my most painful misadventures, whether with the silken purses or their inhabitants, have I seen my skin covered with serous pustules and peeling off in flakes. This time it is a veritable sore, anything but pleasing to the eye.
The aggravation is easily explained. I soaked in the ether some fifty discarded skins. The few drops which remained after the evaporation and which were absorbed by the square of blotting-paper represented, therefore, [[145]]the virulence of a single insect fifty times increased. My little blistering-plaster was equivalent to the contact of fifty caterpillars at the same spot. There is no doubt that, if we left them to steep in considerable numbers, we should obtain extracts of really formidable strength. It is quite possible that medical science will one day make good use of this powerful counter-irritant, which is utterly different from cantharides.
Whether voluntary victims of our curiosity, which, while affording no other satisfaction than that of knowledge, exposes us to an intolerable itch, or sufferers through an accident, what can we do to give a little relief to the irritation caused by the Processionary? It is good to know the origin of the evil, but it would be better to apply a remedy.
One day, with both hands sore from the prolonged examination of a nest, I try without success lotions of alcohol, glycerine, oil and soapsuds. Nothing does any good. I then remember a palliative employed by Réaumur against the sting of the Oak Processionary. Without telling us how he came to know of the strange specific, the master rubbed himself with parsley and felt a good deal the better [[146]]for it. He adds that any other leaf would probably assuage the irritation in the same way.
This is a fitting occasion for reopening the subject. Here, in a corner of the garden, is parsley, green and abundant as one could wish. What other plant can we compare with it? I choose the purslain, the spontaneous guest of my vegetable-beds. Mucilaginous and fleshy as it is, it readily crushes, yielding an emollient liniment. I rub one hand with parsley and the other with purslain, pressing hard enough to reduce the leaves to a paste. The result deserves attention.
With the parsley, the burning is a little less acute, it is true, but, though relieved, it persists for a long time yet and continues troublesome. With the purslain, the petty torture ceases almost at once and so completely that I no longer notice it. My nostrum possesses incontestable virtues. I recommend it quietly, without blatant advertisement, to any one who may be persecuted by the Processionary. Foresters, in their war upon caterpillars’ nests, should find great relief from it.
I have also obtained good results with the leaves of the tomato and the lettuce; and, [[147]]without pursuing this botanical survey further, I remain convinced, with Réaumur, that any tender juicy foliage would possess a certain efficacy.
As for the mode of action of this specific, I admit that I do not understand it, any more than I can perceive the mode of action of the caterpillar’s virus. Molière’s medical student explained the soporific properties of opium by saying: