As measles or influenza fastens upon fresh blood like a plague, so do many of our downtrodden plants become bumptious and aggressive in the stimulating air of a new world, wherever they find a not forbidding environment, and a fair chance to elbow a place for themselves in the struggle for existence. In a less degree, the same conquest is to be noted in America, the old-settled Eastern States having been largely colonised by imported growths, while the indigenous flora retreated with the Red Man to the inland woods and prairies. From the more southerly regions of America, we Europeans have got more than we give, in Indian corn, the tomato, the pineapple, and the hardy potato, that for our damp Western islands has come to be the staff of life as it was on the dry sunny heights of its native Bolivia, though in Britain, as in some parts of the Continent, it had at first to live down most pig-headed prejudices. Besides naturalising the productions of other climates, Kew has the less noted function of exporting our seeds to try their luck abroad, as, for instance, barrels of acorns hence sent to take prosperous root in South Africa. For the timbers, huge, rich, rare, beautiful and useful, of these exotic trees, and for their products, we turn to the Museums and Economic Houses that are the most instructive part of this exhibition. Here Masters Sandford and Merton might spend many days in enlarging their mental prospects. The cane, for instance, chiefly familiar to them on the seat of chairs, or perhaps by a use that renders sitting a property of uneasiness, they will learn from Mr. Barlow to belong to a great race of arborescent grasses, among which the young gentlemen may perhaps be most interested in the raw and manufactured products of the sugar-cane. Here their well-instructed tutor can point out to them how the bamboo, prince of this race, is beneficent to many peoples, supplying them with paper, ropes, hats, weapons, fans, baskets, umbrellas, tents, mats, boxes, also houses, bridges, masts, sails, ladders, fences, flutes, and other tools, weapons and utensils, amply illustrated in the cases of Museums II. and III. Off the Rhododendron Walk there is a garden of feathery bamboos that can make shift to stand our open air. In the same quarter, a division labelled _Betula_ is also calculated to throw a shade over the spirit of Master Merton, if not of the blameless Harry Sandford, this in the vernacular being a tree of knowledge too well known to British youngsters of past generations for its base use, frowned on by latter day humanitarians, but a smiling jest to the poets from Shakespeare to Swinburne-- With all its blithe, lithe bounty of buds and sprays, For hapless boys to wince at and grow red, And feel a tingling memory prick their skins.