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Aug. 25. 1878

Cotyledon umbilicus (Crassulaceæ

Circumnutation of stolon.

Left-Hand stolon:

A plant growing in dish stood on shelf & had emitted 2 long stolons (first 20 inches long: second 22 long). Plate brought & placed under skylight,; stolon & ev with very thin glass filament with [triangle] marks affixed to extremity & supported there, & movement traced on vertical glass: stolon was perfectly straight: though, after it had become bowed,—Copied on true scale

vertical glass. [diagram] drawn in true scale.

From Tip of stolon. 5.75 to from glass.— From tip of stolon to middle of flexure, & therefore probably the part which moved 1 1/4 inch. — (thus calculate actual amt of movement.—

Aug 25th 9° 10' a.m The stolon at first projected horizontally to the length of 4 1/2 inches from support but the ultimate internode (neglecting little minute young terminal one) so began bending down & thus continued from 9° 10' to 12°— See Tracing (A) by 12° 40' had travelled a little to left & & by 1° 25' had risen considerably — it then continued circumnutating in vertical plane till 10° 35' P.m. Next day I conclude that the first great downward movement was due to weight of end of stolon & that middle of internode the more flexible part.— If it had been geotropism the falling wd have continued next day, which did not occur — nor to speak of 27th or 28th.

It is, however, possible that the stolon is acted on by geotropism like secondary radicles, accrdng to Sachs in which case, it wd have bent down only moderately; but in this case

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p. 25.

cotyled umbilic, diagram, showing drawn on 1/2 natural scale, showing whole length of internode at close of one observation, & move, in which it was observed.

The bending shown in the [illeg] internode, probably due wholly to its own weight.

(2

Cotyledon

(Keep original)

the extreme part of ultimate internode wd probably have bent most. — Next day Aug. 26', observed seldomer, & only till between 6° 40' a.m & 5° 20' P.m & during this time ascended twice & descended twice; ending on nearly same level as started. — There can be no doubt about circumnutation in neary vertical plane.

A second The other Stolon which resemble on all other respect the last was observed at the same time, but only 2 inches in length of the terminal portion was allowed to project freely & horizontally. (see Tracing B.— general appearance of stolon like the last This On It During the whole of the 25th it continued from 9° 10'm. to 1° 30 to bend downwards, owing to the its weight down all day—but in evening the bending down was rendered zig-zag by circumnutation— Next day went twice up & twice down.— Apex Closer to glass so not so much magnified ; (make more Light); but after this hour at until 10° 35' P.m it zig-zagged. This same fact deserves, notice for we her see in the zig-zag line the continued effects of the bending down from mere weight & circumnutation: The stolon did not circumnutate, As long as the bending from weight from gravity weight acts energetically, as may be observed in this part as it continued to bend round & quickly downward first on weight : This may be observed case & more especially in the first diagram case diagram & case, where 4 1/2 a longer portion of the stolon of the stem was left unsupported. circumnutation the stolon cease to circumnutate

On the following day (26th) the stolon it moved twice up & twice down, but still continued to fall & in the evening moved from some unknown cause in an oblique line.