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THE MOVEMENTS OF PLANTS. 
By THE Key. GEORGE HENSLOW, M.A., F.L.S., F.G.S. 
[Plate V.] 
T HE old distinction between plants and animals, that the 
latter can move and the former cannot, has long since 
been abandoned as unscientific, and only lingers as a copy-book 
assertion ; but that all plants, even when permanently fixed to 
the soil, have their stems, leaves, flower-stalks, &c., in almost 
perpetual motion, is a discovery of quite recent times, and 
notably due to the investigations of Mr. Darwin. His latest 
work, which bears the title of this article,* is a treatise based 
on the most careful and elaborate experiments on the motions 
effected by the different organs of plants ; and it was thought 
that a brief exposition of the chief of these, as well as of some 
movements peculiar to the parts of flowers not alluded to by 
Mr. Darwin, might be interesting to the readers of the Popular 
Science Review. 
The majority of the movements can be embraced under the 
single term circumnutation and its modifications ; it signifies a 
‘ bowing around.’ The stem, leaf, or other organ, when cir- 
cumnutating, bends to all points of the compass successively, 
with a sort of rolling motion, so that the side which is upper- 
most in any direction becomes lowermost when it points in the 
opposite one. The circles or ellipses thus described by the 
apex of the organ, are most perfectly seen in the circumnutation 
of the stems of climbing plants ; other organs for the most 
part move in ellipses, but with frequent interpolations of 
zig-zags, triangular loops, &c. The projections of such motions, 
when observed for some hours, exhibit most complicated and 
intricate lines ; a great number of these projections are given 
by Mr. Darwin. With regard to the cause of circumnutation, 
Mr. Darwin says that on the whole we may at present conclude 
* The Tower of Movement in Plants. By Charles Darwin, LL.D., F.R.S., 
assisted by Francis Darwin. 8vo. London : Murray. 1880. 
NEW SERIES, VOL. V. NO. XIX. 
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