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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 8° 42', & until 10°. 12' mark travelled over horizontal glass with grt rapidity — Line slightly zig-zag, showing only trace of circumnutation. From 10° 19' to 12° 5' traced on vertical glass still travelled to light, still slightly zig-zag. At 12° 16 had moved laterally, then ascended, again descending, so that it plainly circumnutate — After 5° 30', when light became became dim, seedling began to rise till in zig-zag line until 8°. 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 10° 21'; (See Figure B) it then travelled in a rather straight line than that above traced till 11° 45' when it began to zig-zag— some of the angles being only a little above 90° At 1° 28' on vertical glass. — At 1. 39° 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 5° 10' being as evening became obscure, began to ascend.