4 6 
Analyses of Books. 
[January, 
The Power of Movement in Plants. By Charles Darwin, LL.D., 
F.R.S., assisted by Francis Darwin. London : John 
Murray. 
It is well known that of late years Mr. Darwin has, with his 
usual ability and success, attacked the old traditional notion of 
an absolute distinction between plants and animals. His re- 
searches on the fertilisation of orchids, on insectivorous plants, 
and on the movements and habits of climbing plants, all militate 
against the supposition of an utterly inert and unconscious cha- 
racter so generally ascribed to the vegetable kingdom. Continuing 
his investigations he has now shown, by dint of a prolonged 
course of experiment and observation, that “ all the parts or 
organs in every plant, whilst they continue to grow, are conti- 
nually circumnutating,” — that is, the point of a growing stem, 
&c., is found to describe an irregular circular figure. This 
movement is not uniform, but consists — in some cases at least — 
of innumerable small oscillations. The phenomena thus pro- 
duced closely resemble many of the actions performed, as is 
supposed unconsciously, by the simpler and lower animals. The 
author remarks that “ even among allied plants one may be 
highly sensitive to the slightest continued pressure, and another 
highly sensitive to a slight momentary touch.” 
Mr. Darwin considers that the most striking resemblance be- 
tween plants and animals is the localisation of their sensitiveness 
and the transmission of any influence from the part excited to 
some other part, which consequently moves. It is not of course, 
contended that plants possess a brain or other true nervous 
centre, and a system of nerves by which it is connected with 
the whole body. But it is, to say the least, doubtful whether 
such structures exist in the lowest animals, and it is probable 
that where present they serve merely for a more perfect trans- 
mission of impressions and a more complete intercommunication 
of the several parts. 
The author calls attention to the wonderful character of 
the tip of the radicle, which is remarkably sensitive : — “ If 
the tip be lightly pressed, or burnt, or cut, it transmits an influ- 
ence to the upper adjoining part of the root, causing it to bend 
away from the affected side ; and, what is yet more surprising, 
the tip can distinguish between a slightly harder and a softer 
object, by which it is simultaneously pressed on opposite sides. 
If, however, the radicle is pressed by a similar object a little 
above the tip, the pressed part does not transmit any influence 
to the more distant parts above, but bends abruptly towards the 
object. If the tip perceives the air to be moister on one side 
than on the other, it likewise transmits an influence to the upper 
adjoining part, which bends towards the source of moisture.” 
Taking these various kinds of sensitiveness into consideration, 
Mr. Darwin pronounces it hardly an exaggeration to say that 
