In the following chapters, the movements of a considerable number of plants are described; and the species have been arranged according to the system adopted by Hooker in Le Maout and Decaisne’s ‘Descriptive Botany.’  No one who is not investigating the present subject need read all the details, which, however, we have thought it advisable to give.  To save the reader trouble, the conclusions and most of the more important parts have been printed in larger type than the other parts.  He may, if he thinks fit, read the last chapter first, as it includes a summary of the whole volume; and he will thus see what points interest him, and on which he requires the full evidence.

Finally, we must have the pleasure of returning our [page 9] sincere thanks to Sir Joseph Hooker and to Mr. W. Thiselton Dyer for their great kindness, in not only sending us plants from Kew, but in procuring others from several sources when they were required for our observations; also, for naming many species, and giving us information on various points. [page 10]

CHAPTER I.

THE CIRCUMNUTATING MOVEMENTS OF SEEDLING PLANTS.

Brassica oleracea, circumnutation of the radicle, of the arched hypocotyl whilst still buried beneath the ground, whilst rising above the ground and straightening itself, and when erect—­Circumnutation of the cotyledons—­ Rate of movement—­Analogous observations on various organs in species of Githago, Gossypium, Oxalis, Tropaeolum, Citrus, Aesculus, of several Leguminous and Cucurbitaceous genera, Opuntia, Helianthus, Primula, Cyclamen, Stapelia, Cerinthe, Nolana, Solanum, Beta, Ricinus, Quercus, Corylus, Pinus, Cycas, Canna, Allium, Asparagus, Phalaris, Zea, Avena, Nephrodium, and Selaginella.

The following chapter is devoted to the circumnutating movements of the radicles, hypocotyls, and cotyledons of seedling plants; and, when the cotyledons do not rise above the ground, to the movements of the epicotyl.  But in a future chapter we shall have to recur to the movements of certain cotyledons which sleep at night.

[Brassica oleracea (Cruciferae)’.—­Fuller details will be given with respect to the movements in this case than in any other, as space and time will thus ultimately be saved.

Radicle.—­A seed with the radicle projecting .05 inch was fastened with shellac to a little plate of zinc, so that the radicle stood up vertically; and a fine glass filament was then fixed near its base, that is, close to the seed-coats.  The seed was surrounded by little bits of wet sponge, and the movement of the bead at the end of the filament was traced (Fig. 1) during sixty hours.  In this time the radicle increased in length from .05 to .11 inch.  Had the filament been attached at first close to the apex of the radicle, and if it could have remained there all the time, the movement exhibited would have [page 11] been much greater, for at the close of our observations