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Ig12] CURRENT LITERATURE 251 
a volume which has just appeared from the pen of A. Ptrrer,? a student of 
VERWORN’S, associated with him at Bonn. -PUTrTer’s book will be especially 
interesting to physiologists who have entered the science through studies with 
ment,”’ and still more because of the freedom and general efficiency with which 
he incorporated numerous facts and principles of plant physiology in his 
treatise. There has not appeared previously a book of readable size, were 
is so truly a comparative physiology as is the present volume. About 
fourth of the figures are taken from plant material. 
Having announced in his introduction that the study of all life-processes 
is the field of physiology, and that an understanding of these processes is to 
following nine topics, which form the chapter headings of the book before us 
(i) The substratum of the life processes, (ii) Metabolism, (iii) Nutrition, 
(iv) Exchange of material, (v) Conditions of life, (vi) Energy transformations, 
(vii) Responses to stimuli, (viii) Organs of perception, (ix) Nervous system 
In the first chapter, under “The physical constitution of living substance,”’ 
the author gives a brief but clear presentation of these aspects of colloida 
chemistry, an understanding of which is most necessary to physiological 
thinking. Under “The constituents of organisms,” he discusses water and 
the various groups of chemical compounds that find a place in living beings 
The point is well made that water is to be considered as fundamental to all 
life, and it is shown that, in general, the water content of the active parts of 
plants and animals may be taken to be about the same. 
In the following chapters, of which spatial limitations prevent any con- 
sideration here, the author’s treatment of the various processes and activities 
of organisms is always carried out from the standpoint of physics and chemis- 
try, at least the methods of these sciences in attacking a problem are here 
always evident. Anthropomorphic terms and ways of viewing life-processes 
are rarely admitted and only with proper logical consideration. The aim is 
always to arrive as nearly as possible at the underlying principles according to 
which the different processes go forward, to bring out the cause of each effect 
and the quantitative relations which exist between these. The book empha- 
sizes in a gratifying and encouraging way the considerable degree to which the 
simpler mathematical expressions of physical science are already being incor- 
porated in physiological reasoning. 
While every reader will find certain points wherein he and the author may 
disagree, we have found the volume exceptionally logical in its generalizations 
*Pirrer, A., Vergleichende Physiologie. pp. viiit721. figs. 174. Jena: 
G. Fischer. 1911. 
