10 



CIECUMNUTATION OF SEEDLINGS. Cb*p. t 



CHAPTEK I. 



The CiBCDMNUTATiNG Movements of Seedling Plaittb. 



Brassica oleracea, circumnutation of the radicle, of the arched hypo- 

 cotyl whilst still buried beneath the ground, whilst 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- 

 p^olum, Citrus, iEsculus, of several Leguminous and Cuourbita- 

 ceous genera, Opuntia, Helianthus, Primula, Cyclamen, Stapeli, 

 Cerinthe, Nolana, Solanum, Beta, Elcinus, Querous, Gorylus, Pinus, 

 Cycas, Canna, Allium, Asparagus, Phalaris, Zea, Aveiia, Nephro- 

 dium, and Selagiuella. 



The following cliapter is devoted 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 epicotyl. But in a future chapter we shall have 

 to recur to the movements of certain cotyledons which 

 sleep at night. 



Brassica oleracea (^Cructferce). — 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. 



Badicle. — 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 would have 



