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Sept 5' 1874 Tropaeolum majus Heliotropism

[sketch]

Sept 5th

A seedling with 2 developed leaves had filament fixed longitudinally to plumule plumule with horizontal glass above & vertical glass between plant & light— Placed in N.E window in study.— The seedlings was at first already a little pointed from light,— See Tracing A which shows movement first on horizontal glass & then on vertical glass. Observations began at 8º 42', & until 10º. 12' mark travelled over horizontal glass with grt rapidity — Line slightly zig-zag, showing only trace of circumnutation. From 10º 19' to 12º 5' traced on vertical glass still travelled to light, still slightly zig-zag. At 12º 16 had moved laterally, then ascended, again descending, so that it plainly circumnutate — After 5º 30', when light became became dim, seedling began to rise till in zig-zag line until 8º. 8' when last observation was made.—

Next day (Sept 6th) same plant again observed; seedlings still pointed to light so pot slewed round, & mark did not come on horizontal glass until 10º 21'; (See Figure B) it then travelled in a rather straight line than that above traced till 11º 45' when it began to zig-zag— some of the angles being only a little above 90º At 1º 28' on vertical glass. — At 1. 39º rose & now circumnutated; & it deserves notice that the circumnutation was transverse to direction of entrance of light, instead of as yesterday in line of light. At 5º 10' being as evening became obscure, began to ascend.