Page:Popular Science Monthly Volume 26.djvu/490

474 acid bodies is common to every part of the skin; but it is least felt where the tough outer skin is thickest, and most felt where that skin is thinnest and the nerves are most plentifully distributed near the surface. A mustard-plaster would probably fail to draw at all on one's heel or the palm of one's hand, while it is decidedly painful on one's neck or chest; and a mere speck of mustard inside the eyelid gives one positive torture for hours together. Now, the tip of the tongue is just a part of one's body specially set aside for this very object, provided with an extremely thin skin, and supplied with an immense number of nerves, on purpose so as to be easily affected by all such pungent, alkaline, or spirituous substances. Sir Wilfrid Lawson would probably conclude that it was deliberately designed by Providence to warn us against a wicked indulgence in the brandy and seltzer aforesaid.

At first sight it might seem as though there were hardly enough of such pungent and fiery things in existence to make it worth while for us to be provided with a special mechanism for guarding against them. That is true enough, no doubt, as regards our modern civilized life; though, even now, it is perhaps just as well that our children should have an internal monitor (other than conscience) to dissuade them immediately from indiscriminate indulgence in photographic chemicals, the contents of stray medicine-bottles, and the best dried West India chilies. But in an earlier period of progress, and specially in tropical countries (where the Darwinians have now decided the human race made its first début upon this or any other stage), things were very different indeed. Pungent and poisonous plants and fruits abounded on every side. We have all of us in our youth been taken in by some too cruelly waggish companion, who insisted upon making us eat the bright, glossy leaves of the common English arum, which without look pretty and juicy enough, but within are full of the concentrated essence of pungency and profanity. Well, there are hundreds of such plants, even in cold climates, to tempt the eyes and poison the veins of unsuspecting cattle or childish humanity. There is buttercup, so horribly acrid that cows carefully avoid it in their closest-cropped pastures; and yet your cow is not usually a too dainty animal. There is aconite, the deadly poison with which Dr. Lamson removed his troublesome relatives. There is baneberry, whose very name sufficiently describes its dangerous nature. There are horse-radish, and stinging rocket, and biting wall-pepper, and still smarter water-pepper, and wormwood, and nightshade, and spurge, and hemlock, and half a dozen other equally unpleasant weeds. All of these have acquired their pungent and poisonous properties, just as nettles have acquired their sting, and thistles their thorns, in order to prevent animals from browsing upon them and destroying them. And the animals in turn have acquired a very delicate sense of pungency on purpose to warn them beforehand of the existence of such dangerous and undesirable qualities