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Show 42G MODIFIED CIRCUMNUTATION. CHAP. YIIr. blinds being left suspended. In Fig. 173 the course pursued, between 8.9 A.M. and 7.10 P.M., by one of tlJ.e bypocotyls thus l JJ? Fig. 173. ~0.9'am. 8°25' . . . . t tiou of a hypocot)·l Brassica oleracea: hehotroplC movement nnd cn cumnu a I orizontnl t owards a very dim lateral light, traced during .11 hours, 011 . a 1 1,:igure glass in the morning, and on a vertical glass m the evemug. reduced to one-third of the original scale. exposed is shown. It may be observecl th·a t durinrbr the first 1 this lG m. the hypocotyl moved obliquely from the light, anc ' CHAP. VIII. HELIOTROPISM:. 427 no doubt, was due to its then circumnutating in thjs direction. Sinrilar cases were repeatedly observed, and a dim light rarely or never produced any effect until from a quarter to throequarters of an hour had elapsed. After 5.15 P.M., by which time the light had become obscure, tho hypocoty 1 began to circumnutate about the same spot. The contrast between the two figures (172 and 173) would have been more striking, if they had been originally drawn on the same scale, and had been equally reduced. But the movements shown in Fig. 172were at first more magnified, and have been reduced to only one-half of the original scale; whereas those in Fig. 173 were at first less magnified, and have been reduced to a one· third scale. A tracing made at the same time with the last of the movements of a second hypocotyl, presented o. closely analogous appearance; but it did not bend quite so much towards the Fig. 174. 6?90' light, and it circumnu- 9.oa, 8~16'ann.Sep18.~h; latedrather more plainly. Pltalaris Ganariensis: heliotropic movement Phalaris OanaTiensis.- and circum nutation of a r ath er old coty- Thesheath-Iikecotyledons ledon, t~wards a dull lateral light, traced 0f his on a honzontal glass from 8.15 A.M. Sept. t · monocotyledonous 16th to 7.45 A.M. 17th. Fi o-ure r ed nced pl~nt were selected for to one-third of original seal;. lrJal, because the a, . . . well as~ Y re very sensitive to light and circumnutate ' tOrmerly shown ( F. 49 no doubt ab t th see Ig. , p. 63). Although we felt before a sout~u e .result, some seedlings were first placed the moveme t -west wmclow on a moderately bright morning, and n s of one were traced. As is so common, it movorl |