[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 8° so was well shaken, fixed filament very fine to new seedling with smaller Cot. vertical or not opened. At 8° 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 int 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.—