10 OIBCUMNUTATION OF SEEDLINGS. CaAP. I. 



CHAPTEE I. 



The Cirocmnutatinq Movements of Seedlixo Plahts. 



Brassica oleracea, oiroumnutation of the radicle, of the arcljed hypo- 

 cotyl whilst still buried beneath the groaiid, whiLt rising above the 

 ground and straightening itself, and when erect — Circumnutation 

 of the cotyledons — Bate of movement — Analogous observations on 

 various organs in species of Githago, Gossypium, Oxalis, Tro- 

 pseolum, Citrus, ^sculus, of several Leguminous and Cucurbita- 

 ceous genera, Opuntia, Helianthus, Primula, Cyclamen. Stapel'a, 

 Cerinthe, Nolana, Solanum, Btta, Eicinua, Quercus, Gorylus, Pinus, 

 Oycas, Ganna, Allium, Asparagus, Phalaris, 5Iea, Aveiia, Nephro- 

 dium, and Selaginella. 



The following chapter is dcToted to the circum- 

 nutating movements of the radicles, hypocotyls, and 

 cotyledons of seedling plants; and, when the coty- 

 ledons do not rise above the ground, to the movements 

 of the epi^otyl. But in a future chapter we shall have 

 to recur to the movements of certain cotyledons which 

 sleep at night. 



Brassica oleracea ^Crudferas). — 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. 



Eadicle. — 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 move- 

 ment 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 re- 

 mained there all the time, the movement exhibited woidd have 



