45 A.M.
28th. Temp. 23-24o C. Movement of bead magnified 21 times.
Stapelia sarpedon (Asclepiadeae).--This plant, when mature, resembles a
cactus. The flattened hypocotyl is fleshy, enlarged in the upper part, and
bears two rudimentary cotyledons. It breaks through the ground in an arched
form, with the rudimentary cotyledons closed or in contact. A filament was
affixed almost
* 'Bot. Zeitung,' 1874, p. 837.
[page 47]
vertically to the hypocotyl of a seedling half an inch high; and its
movements were traced during 50 h. on a horizontal glass (Fig. 34). From
some unknown cause it bowed itself to one side, and as this was effected by
a zigzag course, it probably circumnutated; but with hardly any other
seedling observed by us was this movement so obscurely shown.
Ipomoea caerulea vel Pharbitis nil (Convolvulaceae).--Seedlings of this
plant were observed because it is a twiner, the upper internodes of which
circumnutate conspicuously; but like other twining plants, the first few
internodes which rise above the ground are stiff enough to support
themselves, and therefore do not circumnutate in any plainly recognisable
manner.
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