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Pistia stratiotes 1877

Sept 9th. 11˚ A.m. rubbed with sponge 2 small space on 2 leaves & will keep on drops of water — — leaves marked yellow wool.

Sept 13th one of these leaves look yellow where water has lain

― 14'. do—, & there are brown specks on surface. & I think the other leaf looks yellowish.

― 15. whole space where water rested yellowish with brown specks examined under microscope: — Hairs poi directed towards apex of leaf — they are brittle & if leaf rubbed towards base they are very easily broken off, & then water wd. gain access to inside of leaf— but case show how easily this water plant is injured by water getting into tissue.

Distance of tips of 2 almost opposite leaves during previ at night— dotted the line distance during previous & following day. [sketch]

(over)

[8v]

Sept 15th — observed one of the larger plants at night with 2 leaves not far from opposite considerably raised —& measured distance from tip to tip, & next morning measured same distance.

[sketch] during day at night

Sept 18. F. measures a leaf which at night 8˚ 45' P.m. was 41° with vertical & next morning at about 10˚ 8˚. 30 A.m was 65° with vertical, so had fallen 24° — This wd make, I shd think, very little difference in exposure to strong radiation. — These measurements not very careful

[sketch] 41° 65°