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Cassia "sea-side." Heliotropism

Oct 7-8' 1878 Tora

Though the Cots are highly sensitive to light, I had observed that Hypocotyl unusually little so, & therefore determined to trace movement as probably indicating well the transition from circumnutation.— Glass-filaments with triangles were fixed Vertically to 2 vertical seedlings — placed in front of N.E. window with muslin blinds down — sides protected from light.— back open to room.— Day rather cloudy— but at 11° 11° a.m become bright & linen blind pulled down so as to meet muslin in At 11'. 45' pulled down whole linen blind. At 4°, as evening advanced pulled up partly & half of linen-blind & by 4° 30 whole linen blind; & 5° removed muslin blind. — Movement traced on Horizontal glass— Hypocotyl between 8° a.m & 6° P.m, (after which bent from light-side), the Hypocotyl become inclined only about 20° from the perpendicular instead of as with most seedlings almost 90°— Horizontal glass 10 inches above soil in pot, & left Hand seedling 1 1/2 inches High— Right-Hand seedling 1. 25 high.— If whole Hypocotyl bends, Tracing Tracing not greatly magnified— (As guide for magnification of Tracings.) (In another pot, I found in one tall seedling the upper .7 of inch of Hypocotyl was bent to light; in a shorter one only .45 thus bent)

[in margin:] I omitted to observe How much bends— I believe only upper 1.2 inch.

Fig I The 2 Cots were nearly at right angle to direction of Light— This Tracing interesting. interesting : at 8° a.m. Oct 7th Hypocotyl vertical, it then tra bowed slowly till 6° to Light in zig-zag line; making in afternoon & evening 2 small circumnutation. After 6° apogeotropism drew it from light & course was slightly zig-zag.— At By 7° a.m on Oct 8th had returned to nearly same spot whence it started in previous

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Cassia — sea-side

morning. On this day Oct 8th seedling was kept whole time in dark & now it circumnutated about same spot.—

Fig II. (The 2 Cots were nearly in line of Light-source) differs in Hypocotyl having moved to light in singular course, but still zig-zag, with one minute circumnutation.

After 6° P.m the return course through apogeotropism was much more zig-zag & one of was not complete during the night; for was continued in the dark, in strongly zig-zag line on following day Oct 8th till 10° 15 P.m. — The whole course from 6° P.m on 7th to 10° 15 P.m on 8th course consisted of circumnutation modified by apogeotropism..

(In light Fig I the circumnutation in the dark on the 8th is seen partially drawn out on the 7th by the action of light. Heliotropism)

good case of apogeotropism [illeg]