Recently Miss Elizabeth A. Simons timed the rate of growth of the same plants at the University of Pennsylvania. They seem to have been stimulated by the exhilarating atmosphere of the United States, for they were all growing faster. The Hop did its turn in 1 hr. 5 mins., Phaseolus took from 1 hr. to 1 hr. 20 mins., Convolvulus 57 mins. only, Lonicera from 1 hr. 43 mins. to 2 hrs. 48 mins., and Wistaria 2 hrs.[138] But there are curious variations in the rate at which these plants revolve. [138] _Trans. and Proc. Bot. Soc. Pennsylvania_, Session 1897-8, vol. 1, No. 1. Thus when coming towards the light they go as fast as they can, but revolve more slowly, and as it were reluctantly, away from it. It has been found in one case that the shoot took thirty-five minutes to do the semicircle towards the light, and an hour and fifteen to twenty minutes going away from it, but this is not always the case, for sometimes the reverse takes place[139] (Baranetzki). [139] Pfeffer, _Pflanzen-Physiologie_, vol. 2, p. 412. These twining plants are not very common in Great Britain, and indeed in Europe. Some of them move or twine to the right (in the same direction as the hands of a watch or of the sun), such as Convolvulus (Bindweed), Phaseolus, Ipomoea, and Aristolochia. Others, like the Hop, Polygonum, Convolvulus, Honeysuckle, and Elephant's Foot, move in the opposite way from right to left, or "widder-shins." But there is nothing very important in this distinction, for the Bittersweet may be found twining in either direction, and in some plants part of a stem may be twining one way and the other in the opposite direction. It is in the tropics, and especially in the rank, dark, moisture-laden atmosphere of the coast jungle forests, that these twiners attain their greatest development. They show the most extraordinary variety. Sometimes a twiner hangs in elegant festoons from branch to branch, forming a convenient suspension bridge for monkeys. Sometimes four or five are wound round one another or twisted together, so that they look like some gigantic cable. In other cases they are knotted, looped, tangled, and twisted in the most inextricable manner. Some creepers are flat, like green ribbons or broad bands. In others the dense mass of old, thick creepers and twiners round some sturdy trunk becomes so thick and so fused together that when the trunk dies the lattice-like arrangement of these creepers may keep them upright although the original supporting trunk is quite rotten and decayed away. More usually, a tree will become unhealthy because its branches are overladen with the dense foliage and flowers of heavy lianes, and because both trunk and branches are so strangled in the embrace of great creepers that they cannot expand and develop in the proper way. Then a storm will overthrow the dead giant of the forest, and these creepers, entangled with all the surrounding trees, will produce ruin and destruction all around.