s ' NATURE 
313 
THURSDAY, JANUARY 31, 1907. 
" THE PLANT AS MACHINE. 
Plant Response as a Means of Physiological Investi- 
gation. By Prof. Jagadis ‘Chunder Bose. Pp. 
XXxvili¢781; with 278 illustrations. (London: 
Longmans, Green and Co., 1906.) 
HE emotions that will be aroused by this book in 
different classes of readers may well be very 
dissimilar. A biologically equipped reader with no 
special knowledge of plant physiology will experience 
dazzled admiration for the logical, progressive way in 
which the author builds up, not in words, but actually 
experiment on experiment, a complete functioning 
plant from three simple conceptions. These concep- 
tions, which will be critically considered later, are 
briefly the following :—stimulation, the transference 
of external energy to the plant; contraction, the con- 
stant ‘‘ direct response ’’ of plant-cells to stimulation ; 
expansion, including growth, the ‘* indirect response ”’ 
to stimulation. 
This present book, big as it is, is devoted almost 
entirely to the mechanical responses of plants; another 
volume is promised on electrical responses. By 
mechanical responses we are to understand all move- 
ments, in the widest sense, not only the obvious move- 
ments of sensitive and sleeping plants with all geo- 
tropic and heliotropic movements, but also. the move- 
ments of expansion in growth and the pumping of 
water up the plant, and, further, ‘‘death-spasms ”’ 
and all the minute shrinkages of unspecialised cells 
produced by stimulation. All these vital manifest- 
ations are dealt with in sequence, passing from the 
simple to the complex, and in them the author finds 
nothing that cannot be interpreted in terms of his 
three primary conceptions. 
Another type of reader, a student of plant physio- 
logy. who has some acquaintance with the main 
classical ideas of his subject, will feel at first extreme 
bewilderment as he peruses this book. It proceeds so 
smoothly and logically, and yet it does not start from 
any place in the existing corpus of knowledge, and 
never attaches itself to it with any firm adherence. 
This effect of detachment is heightened by the com- 
plete absence of precise references to the work of 
other investigators. The student, puzzled by the 
number of original conceptions, may hesitate between 
accepting and rejecting the whole book, and will prob- 
abiy wait, with judgment suspended, until someone 
with more conventional ideas of the plant than Dr. 
Bose has re-investigated the phenomena and interpret- 
ations here brought forward. 
The extreme isolation of this book is no doubt to 
be explained by the author's scientific past. Dr. Bose 
was, we believe, a physicist originally, and has been 
drawn into biology by following up the similarities 
which he has announced between the electrical and 
‘other responses to stimulation given by metal bars 
and by living animal or vegetable cells (see ‘‘ Response 
in the Living and Non-Living,”’ 1902). Dr. Bose 
NO, 1944, VOL. 75 | 
| preaches thé continuity of response in all matter, living 
or non-living, in metal wires; muscle fibres, sensitive 
plants, and vegetable cells in general, and has de- 
scribed effects’ ‘in metals -eorresponding to fatigue, 
latent’ period, summation of stimuli, temperature- 
optima, and characteristic vital phenomena. 
From this similarity of the effects of stimulation he 
passes to assuming a similarity of mechanism in all 
these cases. In metal bars the mechanism of 
course, physical, and there is no question of stored 
chemical potential energy liberated on stimulation : 
this purely physical interpretation is by him extended 
to living cells; molecular change of protoplasm, not 
chemical change, is all he recognises, and when a 
temporary storing of energy has to be admitted he 
considers it a purely physical accomplishment. ! 
The originality of this and of other fundamental 
views stated or implied in this book makes it more 
important for a reviewer to consider these conceptions 
critically than to give an outline sketch of the whole 
book, interesting and stimulating though it is. 
Dr. Bose conceives the living organism as a deli- 
cate responding physical machine the responsive 
movements of which are brought about entirely by 
external stimuli. All. external stimuli, chemical, 
thermal, mechanical, photic, &c., produce the same 
direct response, namely, contraction of the cells with 
active expulsion of water, a negative turgidity-vari- 
ation, and a negative electrical variation. 
These effects are observable, not only in so-called 
“sensitive ’’ plants, but in all living parts of plants, 
and it is a definite advance, due to Dr. Bose’s delicate 
experimentation, to have it shown that all radial 
organs, stems, styles, stamens, &c., shorten on stimu- 
lation. 
other 
is, 
In addition to the direct response of contraction 
there is also an opposite effect, the so-called indirect 
response of expansion, which is produced at a distance 
from the stimulus by the water expelled in contraction 
causing distension or expansion of cells elsewhere, 
with accompanying positive turgidity-variation and 
positive electrical variation. Of this nature, an in- 
direct effect of stimulation merely, is the characteristic 
vital phenomenon, growth. 
Much, then, is made to depend upon stimulation, 
yet the author holds the astonishing view that all the 
work done by the plant is the real equivalent of 
energy received by the impact of stimuli from with- 
out. The author does not even attempt to impart 
verisimilitude to this view by including food materials 
among his stimuli. For him the living organism is 
not a combustion engine doing work by the energy 
liberated chemically in oxidising carbon compounds, 
but it is just such a physical machine as a windmill, 
requiring blows rather than food to make it work, 
and the last picture in the bool: is indeed a figure of 
this windmill. We fear that, valiant and therough as 
Don Quixote in his attack upon this misconceived 
phenomenon, the author hardly avoids a similar fate 
by starting with an inverse misconception. 
It is easy to see that Dr. Bose acquired this view 
of stimulation originally from his experiments on the 
P 
