[70]

(a

1877

Red Cabbage

Rate of Movement of young leaf & of Cotyledons

Nov. 10 I observed one of the true leaves the third formed on the plant, & a little over, including petiole 3/4 of inch in length. Placed the pot under cd M. with micrometer, so that each division was 1/500 of an inch. Observation made in study in middle table, dark morning, & as the movement was obliquely from light, cd not have been heliotropism. Movement rather quicker than here given as the it was not quite at r∠ to the divisions the

[Data]

[in margin:] (True leaf)

Nov. 11. I observed a young seedling in which which only the larg neither Cot. had fully opened, & fixed short hair of glass to top of stem & put under 2 inch-object glass & micrometer of which each division equalled 1/500 of inch, & the point passed over 4 divisions in 2' 38", so it wd have passed 5 divisions in 3' 17". It must have gone rather quicker for it got slightly out of focus. The plant whilst thus observed was placed on middle study table & day very dark & cloudy.

I then moved pot into window where it got more light & now F. [Francis] observed that it passed 5 division in 53", in 55" & 65'. It was a most curious spectacle. It is not certain whether it was now moving from or to light but I believe former. Anyhow I certainly saw it, after having been kept for

(b

Red, Cabbage

5' in very obscure light, move with great rapidity from light.

This looks as if l increased lights stimulated movement of nutation.

(Nov. 12th The seedlings were kept in Hot-House during night & Watered & brought down to House at 8º so was well shaken, fixed filament very fine to new seedling with smaller Cot. vertical or not opened. At 8º 30' observed it on middle study Table Keeping off all most light by board in front, the odd oscillation was strongly marked, the point of filament oscillating in all directions about 1/500th of inch. This was observed for at least 5'.— Pot then put into study-window clear bright morning, & similar oscillation was observed carefully for 4 minutes— There was slight movement, prevailing over the oscillation obliquely from light. The plant was then almost completely screened protected from light & allowed to rest for 1/4 of Hour. Was then observed oscillations still went, perhaps less & in 6' moved barely 2/500 from light.

Protected from light & left to rest for 1/2 hour, the point then crossed 5 divisions, obliquely towards light in 7' 7", still oscillating somewhat. Was again protected from light for 1/2 hour & now still oscillating slightly crossed travelling towards light division in 5' divisions in 5'

Now left exposed freely to light of N.E. window for 25 & the point now moved much slower for it crossed only 2 divisions still moving towards light & oscillating a good deal backward & forwards in 5': therefore it wd have crossed 5 divisions in 12' 30"; I conjecture will soon nutate in opposite direction; or probably whole stem moving toward light & nutating in opposite direction. After being an hour in dark crossed 5 division toward light in 3' 18", but it is impossible to say how much due to Heliotropism & how much to Nutation

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Nov. 13 /77

Red Cabbage

Nov. 13th placed the seedling with glass filament observed yesterday in completely darkened room, (Franks) & the point oscillated backwards & forwards through a space of very nearly almost 2/500' of an inch, at the same time travelling very slowly in one direction. This plant was 1.7 inch in height from ground to summit of Cot.

I affixed glass filament to stem of a taller seedling, 2.3 inches in height, (as before measured) & observed in complete darkness, the plant had been exposed to light of N.E window only whilst filament was affixed, & had then been kept for about 1/2 hour in darkness before being observed: The point travelled over 5 divisions of the micrometer (ie 1/100th of an inch) in 1' 20", & this makes me believe fully in Franks observations yesterday.

After an interval of a hour, observation renewed, conditions all the same & now point travelled over 1 division of micrometer in 3'. 6", so wonderfully slower. I have observed before that rate differs greatly.—