[394]

Dec. 17'

Tropæolum movement of seedlings under ground

Tom-Thumb. var. (Used)

Left-Hand Plant Uncovered a seedling of which arched hypocot. stem covered by crust of earth & fixed filament fixed to basal half & then crumbly earth placed round again— Traced Diagram (1) on Horizontal glass, protected from light. Tracing much magnified, viz 27.12 times — Made 2 small circles between 9° 20' & 4° 30'; then began the great movement due to bending back of basal part of stem from the upper or cot-bearing half—; by 10° 10' had moved off glass. — The cots. are developed rather late & this will account for the straightening of the hypocot. stem occurring rather late & this & next observations important as showing circum-nutation before hand.

As this plant not tied the great movement not due to excitement from the thread.

Right-Hand seedling: a silk thread was passed round middle of young cots. & upper part of basal half of hypocot. stem & all rest done as in last experiment. Tracing magnified about 18.21 times. See tracing II. — Between 9. 20' z. & 6° made an irregular circular, strongly zig-zag. — then moved far in one direction, which after 8°. 15 was somewhat changed & by 10°. 10' had swept far off glass. This great movement due to straightening of hypo bending back of of basal part of Hypo-cot stem & was nearly in opposite direction to that in Tracing I, because seeds happened to lie in reversed positions.