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Show 10 CIUOUMNUTATION OF SEEDLINGS. 0HAI'. l. CHAPTER I. ·rHE omouMNUTATJNG MovEMENTs oF SEEDLING PLAN'l's. Uraseica oleracea, circumnutation of the radicle, of the arched hypocotyl whilst still buried beneath tbe grouud, whiM 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 Gitbago, Gossypium, Oxalis, Troproolum, Citrus, 1Esculus, of several Leguminous and Cucurbitaceous genera, Opuntia, Heliantlms, Primula, Cyclamen, Stapclia, Corinthe, Nolana, Solanum, Beta, Ricinus, Quercus, Corylus, Pinus, Cycas, Canna, Allium, Asparagus, Phalaris, Zea, A vena, N ephrodium, and Selaginella. TnE 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 (Cruciferce).-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 ·n 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 OliAP. I. BRASSIOA. 11 been much greater, for at the close of our observations the tip, instead of standing vertically upwards, had become bowed down wards through geotropism, so as almost to touch the zinc plate. As far as wo could roughly ascertain by measurements made with compasses on other seeds, the tip alone, for a length of only -do to yg0 of an inch, is 11cted on by geotropism. But the tracing shows that the basal part of the radicle continued to circumnutate irregularly during the whole time. The actual extreme amount of movement of tho bead at the end of the filament was nearly ·05 inch, but to what extent tho movemon t of the radicle was magnified by tho filament, which was nearly ! inch in length, it was impossible to estimate. Fig. 1. Bmssica oleracea: circumnutation of radicle, traced. on horizontal glass, from 9 A.M. Jan. 31st to 9 P.llf. Feb. 2nd.. Movement of bead at end. of filament magnified about 40 times. Another seed was treated and observed in the same manner l>ut the radicle in this case protruded ·1 inch, and was not Ji'·g·,·~--\\, \ Brassica oleracea: circumnutating and geotropic movement of radicle traced on horizontal glass during 46 hours. ' fastened so as to project quite vertically upwards. The filament was affixed close to its base. The tracing (Fig. 2, l'educed by half) shows the movement from 9 A.M. Jan. 31st to 7 A.M. Feb. 2nd; but it continued to move during tho whole of the |