[233]

Feb. 10' Lychnis githago (Used)

One Cot. higher or longer than other.— Yesterday many Cots were open about 30°(?) marked 7 plants; this morning 8° 15' all closed & vertical! I am neary certain that Cots. more closed at 6° P.m. than during day. Fixed glass filament beneath Pots at right angles to them & facing, observed in dark with cylinder illuminated from above.— First dot at 8° 17'

(Used)

a Pot some seedlings were dimly illumin from vertically above & a glass filament was fixed Hor transversely to the hypocot cotyl close of one close beneath the petioles of the cotyledons & the seedling were illuminate from vertically above, & its Its movement was traced (being magnified about 17 times) on a Hor glass from 8° 15' a.m on one day to 12° 15' on the following day, ie during 28 hours. The course followed is shown in fig 11., reduced to half.; The lines broken dotted line showing representing the course general course direction movement during the night. The stem moved in all directions; The line from right to left, was being parallel to the blades of the cotyledons. as the plant stood, & the others lines never rising The actual distance amount wa distance travelled from side to side by the tips of the stips by the bed was at least .12 Probably alm .2 of an inch,: but it is impossible to know this speak accurately on this head, as with the more obliquely the plant was viewed, after it had moved plant after moving for some time was viewed obliquely the the more the tracing on the been exaggerated)

(over)

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[calculations not transcribed]

Used

(while the seedling was kept in the greenhouse on Feb 9th, the Cots, in the middle of the day → (Feb 9th) open & formed together an angle estimated at 30°; at 6° P.m. they were nearly closed & next morning, at 8° a.m (Feb 10th) they were completely shut or asleep. The plants were then placed in a box with a glass cover, so as to be feebly illuminated from above whilst the circumnutation of the hypochil was observed; & the cotyledons did not open in the least all day, nor on the next day

(Feb 11th) as long as they were dimly illuminated. they were then replaced in carried back to the greenhouse at 12° 30' & in 2 1/2 hours though the day was dull & foggy some of them began to open; so that some & in an addition 1 1/2 hour, the the some of cotyledon of some formed an angle together of between 20° & 30° & & stems of all the plants were had been greatly bowed greatly to the light; B 7°. 30' P.m. they the cotyleds were completely closed. On the following morning (Feb. 12th) they were closed at 7° 30 a.m, partially opened by at 9° all pretty fully at 11° ; at 12° 30 they formed were open to the extent of & at noon were to the ex of 38°; & at 4° 30', to 62° It is thus obvious that the cotyledons move vertically up & down It is thus evident that the cots of capable of much movement, but they are not sensitive to a touch, by which time the sun shone & the day bright.

We have met with no other instance in which their opening & shutting of the Cots has been is so directly dependent on the action of the light. With mature plants for instance it is known that if placed they are placed in the dark during the day the true leaves generally place themselves in the position of so called sleep