There are several of these unconscious American importations in various parts of Britain, some of them, no doubt, brought over with seed-corn or among the straw of packing-cases, but others unconnected in any way with human agency, and owing their presence here to natural causes. That pretty little Yankee weed, the claytonia, now common in parts of Lancashire and Oxfordshire, first made its appearance amongst us, I believe, by its seeds being accidentally included with the sawdust in which Wenham Lake ice is packed for transport. The Canadian river-weed is known first to have escaped from the botanical gardens at Cambridge, whence it spread rapidly through the congenial dykes and sluices of the fen country, and so into the entire navigable network of the Midland counties. But there are other aliens of older settlement amongst us, aliens of American origin which nevertheless arrived in Britain, in all probability, long before Columbus ever set foot on the low basking sandbank of Cat Island. Such is the jointed pond-sedge of the Hebrides, a water-weed found abundantly in the lakes and tarns of the Isle of Skye, Mull and Coll, and the west coast of Ireland, but occurring nowhere else throughout the whole expanse of Europe or Asia. How did it get there? Clearly its seeds were either washed by the waves or carried by birds, and thus deposited on the nearest European shores to America. But if Mr. Alfred Russel Wallace had been alive in pre-Columban days (which, as Euclid remarks, is absurd), he would readily have inferred, from the frequent occurrence of such unknown plants along the western verge of Britain, that a great continent lay unexplored to the westward, and would promptly have proceeded to discover and annex it. As Mr. Wallace was not yet born, however, Columbus took a mean advantage over him, and discovered it first by mere right of primogeniture. In other cases, the circumstances under which a particular plant appears in England are often very suspicious. Take the instance of the belladonna, or deadly nightshade, an extremely rare British species, found only in the immediate neighbourhood of old castles and monastic buildings. Belladonna, of course, is a deadly poison, and was much used in the half-magical, half-criminal sorceries of the Middle Ages. Did you wish to remove a troublesome rival or an elder brother, you treated him to a dose of deadly nightshade. Yet why should it, in company with many other poisonous exotics, be found so frequently around the ruins of monasteries? Did the holy fathers--but no, the thought is too irreverent. Let us keep our illusions, and forget the friar and the apothecary in 'Romeo and Juliet.'