[99]

Oct 6th. 1878'   Phalaris — Exposure to Lamp in dark room at different distances — 4 seedlings of very nearly equal height, viz .66 high. — in nearly straight line transversely to direction of light = angles measured— chord of = [sketch]

Exposed to light at 8° 50' angles measured at 12°. 50' i.e exposed for 4° at 20 ft I could see that ther were large figures on my watch. (over) (over)

(1) at 2 ft 0, 10, 3, 11, Two others about same height 10, 6 The 0 was really well bent

(2) at 4 ft 9, 12, 17, 7

(3) at 8 ft 12, 9, 4, 19, same height further away Another about same height 7°

(4) at 12 ft 12, 8, 8, 3

(5) at 16 ft 0, 9, 10, 11 not bent as much as 9 N.B, the 0 & the 9 one were really bent about equally

(6) at 20 ft. 14, 8, 11, 0 quite straight Some of this pot are almost straight but bent inclined so as to give an angle.

It is impossible to trust in the least the angles, because the curvature of the tip is the real indication, & a slight inclination of the se whole seedlings, & few of them are absolutely vertical, affects the angle, as this is measured by a plumb line

see diagram at Back

[99v]

To give better idea of degree of darkness, I made with Indian Ink a chain of wide dots on white card. opposite pot at 12 ft from Lamp. I cd just see a dot .06 of inch in diameter ie, a little above 1/20' of inch— at the 16 ft Pot I cd see dot .09— & at the 20 ft pot a dot .14 in diameter, but in each case not the smaller ones. The tall A dot .14 very large in appearance.

[sketch]

A an inclined seedling not curved to light

B a Seedling which was upright & gave same angle from bowing

(1

Oct 7th 1878 Phalaris Rate of Movement to Light

I have no doubt raised in darkness

Two seedlings observed in dark room with Paraffin Lamp, 1 foot from seedlings & light passing through Bichromate. They were so placed that they were circumnutating to right or left & a little from the light. The Bichromate was then removed & time recorded when they began to move to light— A minute triangle of paper shell-laced to apex— Each division of micrometer 1/500 of inch—

Pot I. seedlings .75 of inch long.— after 4' 30" still moving transversely to light— was next looked at 7' after Bichromate removed, had now travelled about 2/500 apparently (?) from light, so must havebeen affected by light about 5' or 6' after Bichromate removed— After 8' had moved considerably from light micrometer then rearranged, & — Some Directly afterwards was had travelled at the rate of 5/500 in 3'— It then moved very slowly, for after 12' 43" from rearrangement of micrometer had moved only 10/500 in 12' 43"

Pot II. you seedlings of same age only .45 high. At 4' 30" after removing the Bichromate had 1/500 from light, so must have begun moving to light about 4' after removal of Bichromate.

After 17' 30' from commencement removal of B. had moved 5/500 — During next 10' moved hardly at all; then recommenced moving from light, & in next 6', moved 5/500 — (ie 10/500) from starting point.)— During next 11' moved 8/500 more additional, all directly to light.

(2

Oct 8th. 1878 Phalaris (Time required for Light to cause movement.

Exposed seedlings 1/4 of inch high to Paraffin Lamp 2 ft distance. Seedling was moving almost directly from light. — Removed Bichromate: in 2' 30" had moved 1/500 from light: in 5' 30" had moved 2/500 from light: in 8' had moved 3/500 from light: in 11' was at same spot: in 14' 10", light had now acted & opposed circumnutation, & had moved 1/500 in opposite direction & to light: in 4' 50" had moved another 1/500 from light. Therefore it appears that light (2 ft distance) counteracted opposite circumnutation in: about 13'

[102]

Perhaps taller Cots move slower??

Oct 8 1878

Phalaris seedling 12 1/2 mm high, —In inches = 1/4 of inch

With the bichromate before it, it was moving nearly transversely to the line joining the plant & the light & slightly (really) away from light

It began to move to the light in 7 1/2 minutes, then moved away from lamp & did not begin to move permanently to light till 14 minutes from start

Temperature varies roughly speaking between 19. C or 20 C with bare lamp & 17 C with bichromate

Seedling 17 mm high = about .66 high

Going transversely & if anything certainly away from light

Hardly observed long enough

Began to move to light in 6 minutes, & in after 2 1/2 minutes during which it moved steadily to light, it was moving quickly—

Seedling not measured — This important

Going transversely & slightly away from light

In 9 minutes it began to move to the light & moved steadily but slowly for 6 minutes in same direction. The 15 minutes away from lamp, then 11 minutes rapidly towards lamp On the whole it did not move permanently to light for 30 minutes.