1906] CURRENT LITERATURE 149 
balanced so as to record the average rate of growth as a straight horizontal 
line, any fluctuation, even the slightest, showing as deviation from this horizontal 
line; and the magnetically controlled heliotropic recorder, utilizing the optic 
lever yet avoiding the use of light within the plant chamber, except that which 
is the stimulus. . 
One striking feature of all the apparatus, aside from its ingenuity, is the 
high magnification which it permits. This is at once an advantage and a 
danger; but consistent results, if critically controlled, ought to guard against 
_ Serious error. 
The book is not without errors, both of reasoning and fact, into which the 
author has fallen by reason of some unfamiliarity with his materials. No one 
could justify himself in accepting as established all the deductions from the vast 
number of experiments detailed in the book; they must be verified sooner or 
later by other observers. To our knowledge some have already been repeated 
(some of those, for instance, on the variation in electric potential resulting from 
stimulation, in Dr. HarPER’s laboratory at the University of Wisconsin) with 
concordant results. But whatever the future may show as to the accuracy of 
details, this book may be acclaimed as a path-breaking one; for it shows a method 
of attack and a refinement of instrumentation for the study of the phenomena 
of irritable reactions in plants that are sure to be of the utmost service. It is 
rather remarkable, indeed, that we have had so few recording instruments in 
the service of plant physiology, and that we have been content, for example, with 
magnifications of 10 or 20 times in the auxanometer, where Bose finds 1,000 or 
€ven 10,000 practicable with his crescograph. . 
The fundamental thesis of the book is that the underlying response to stimuli 
isalike in plants and animals; is alike in all plants and in all parts, with all stimuli; 
and is universal. This response, however diverse its modes of expression, con- 
sists of two very simple and well-defined factors, contraction and expansion; 
the former the direct effect of stimulation, the latter the indirect. Mechanical 
response is always by a concavity of the more excited side and may or may et 
ccur; electrical response can always be detected; growth is merely a multiple 
Tesponse; at death (near 60° C. for phanerogams) a sudden and irreversible 
molecular change takes place, attended by an excitatory contraction. The 
Phenomena of fatigue, of staircase response when the organ is at first sluggish, 
of tetanus, of the polar effects of electric currents, of variation in electric poten- 
tial, of transmission of stimuli, and of rhythmic responses—all can be demon- 
strated in plants as in animals, giving evidence in greater detail of the essential 
unity. With this Bose is more impressed and on it he lays more stress than the 
casé demands; for it is by no means so novel an idea to botanists as to most 
zoologists. 
Of all the fifty chapters in the book none are so unsatisfactory as those on 
the ascent of sap, constituting. part V. Bose holds that he has demonstrated 
the ascent of water to be due to the physiological activity of living cells whose 
Suctional response is coordinated by the passage from point to point of an exci- 
