[1]

Desmodium gyrans

(Jun 22d & 23d 1878 circumnutation of leaf)

A fine healthy young plant 8 inches high bore nearly full-grown vigorous leaf, which with petiole was 3 3/4 inches in length.

Horizontal during day, tip 6 inches from vertical glass: [sketch]

Observed under skylight. — (Temp on 22d 19°-21° — on 23 21°) See Tracing. Course Course during middle of day very complex, observed generally at intervals of 1°, so lines are straight; but between 12° 34' & 1° 5' (ie 29') 5 observations made & line zig-zag —

So again between 2° 24' & 3° (ie 36') 8 observations were made & again line wonderfully zig-zag.— Again 2 observations at 4° 46' & 4° 50' — so that if dots made & traced every 5' & lines joined by lines the course though following that figured would have been extraordinary crooked crooked or zig-zag. Great circumnutations made up by small ones. — On other hand after 5° 48' when sleep position position was being assumed, though observations taken every 4' or 5' lines almost absolutely straight. Case like that of strong Heliotropism or Geotropism. The tendency to go down late in evening must be inherited & not direct effect of lessened light; for on next morning (24th) the plant was covered up under bell-glass & cloth from 8° 37' am to 2' P.m, & though it sank considerably had not by 2° nearly reached the drooping dependent nocturnal position.—

66.00

37

5.23