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MB. DAEWIN ON CLIMBING PLANTS.

The young internodes of the Lophospermwn are sensitive as wellas the petioles, and by their combined movement seize any object.The flower-peduncles of the Maurandia semperfiorens revolvespontaneously, and are sensitive to a touch, yet are certainly use-less for climbing. The leaves of at least two and probably of mostof the species of Clematis, and of JFumaria and Adlwnia , spon-taneously curve from side to side, like the internodes, and are thusbetter adapted to seize any distant object. The petioles of the per-fect leaves, as well as the rudimentary or tendril-like leaves ofTropceolwn tricolorim move spontaneously and slowly towardstheir own stem or the supporting stick, which they then clasp;these petioles also show some tendency to contract spirally. Thetips of the uncaught leaves of the Gloriosa, as they grow old, con-tract into a flat spire. These several facts are interesting, as weshall see, in relation to true tendrils.

It was observed in some cases that, as with twining plants, sowith leaf-climbers, the first internodes which rise from the grounddo not spontaneously revolve; nor are the petioles or tips of thefirst-formed leaves sensitive. In certain species of Clematis thehigh development and spontaneous movements of the leaves, withtheir highly sensitive petioles, apparently have rendered almostsuperfluous the spontaneous movements of the internodes, whichhave consequently become enfeebled. In certain species of Tro-pceolum it would appear as if both the spontaneous movements ofthe internodes and the sensitiveness of the petioles have becomeenfeebled ; and in one species they have been completely lost.

Part III.— Tendeil-beaeing Plants.

By tendrils I mean filamentary organs, sensitive to contact andused exclusively for climbing. By this definition, spines or hooksand rootlets, all of which are used for climbing, are excluded.True tendrils are formed by the modification of leaves withtheir petioles, of flower-peduncles, perhaps also of branches andstipules. Mohl, who includes with true tendrils various organshaving a similar external appearance, classes them according totheir homological nature, as being modified leaves, flower-pedun-cles, &c. This would be an excellent scheme ; but I observe thatbotanists, who are capable of judging, are by no means unanimouson the nature of certain tendrils. Consequently I will describetendril-bearing plants by natural families, following Bindley,and this will in most, or in all, cases keep those of the same homo-