But quite apart from these merely restless plants, and there are thousands of different kinds which are known to move slightly, at least during their young stages, are a few more decidedly active ones that are seemingly irritable. At least they show peculiar movements if touched, and at night. One of the best known is the sensitive plant from tropical America. Its twice compound leaf is composed of many tiny leaflets which upon the slightest touch close up and apparently wither on their stalk at once. In five seconds after the leaf is touched it will appear like a wilted wreck. If the jar is sharp enough the whole plant will droop, and the response to a sudden jar is almost electrically quick in its action. And yet all this sudden wilting, actually caused by a quick loss of turgor, is slowly repaired and the plant carries on quite normally again until another shock renews its irritable response. This plant does the same thing gradually during the night, except that the leaflets recover their normal position only with the rise of the sun. From India comes the most remarkable of all plants so far as movements are concerned. For in the telegraph plant the movements are so regular and long continued that irritability might almost be said to be continuous. The plant is a low shrub or herb with compound leaves, and the terminal leaflet, which is much larger than its neighbors on either side of their common stalk, performs a motion that describes with its tip an irregular oval or ellipse. But the movement is not steady; it goes by a series of slight but perfectly distinct jerks. It takes about two minutes for the leaf to complete its cycle, and it is this jerky movement that has given the plant its name. During the night its leaflets stop this apparently quite useless performance, the cause of which is quite unknown. It is often grown in greenhouse collections where its strange movements may be seen on any sunny day. Many other cases of the restlessness or irritability of plants could be given, and nothing has been said here of the curious movements of some insectivorous plants as they have already been mentioned. The very considerable movements of certain flower and fruit organs will also be considered elsewhere. * * * * *