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Sept 18. 1878.

Celery Heliotropism— fairly bright light

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Sept 18'—Two Pots of seedlings Placed before S.W. window— Cloudy day & rain, but clouds high, so not very extremely dark. Traced on Horizontal glass— dark on all side, except window— Height from ground to glass 9 3/8 inches— Height of Hypocotyls of both seedlings .45 of inch so can calculate magnification.

Left Hand seedling Fig I. younger than other & moved quicker, so that at 11° 35' was on margin of glass, ie in 3°.

Right Hand seedling, Fig II. seedlings same height, but older for plant plumule formed plain bud; observed from 8° 35 to 2. 5', ie for 5° 30', when went off glass— showing how much slower it — The slight bowing of line, due to Hypocotyl rests being quite a little curved laterally, & as it moved to light straightened itself. — Both seedlings vertical next morning (19th) at 7° 30'

I can select good series. (of 4 or 5 tracings)

It is very remarkable the tendency to a single circumnutation in other tracing of having circumnutation in middle of day. Perhaps of acceleration of movement later in day, but this not trustworthy as tracings always oblique later in day.— I think it will be good to give several Tracings of Celery & several of Phalaris, & not of many other plants—