144 BOTANICAL GAZETTE [AUGUST 
of the mode of absorption of gases, which is repeatedly spoken of as though 
it were merely their diffusion from the external air into the intercellular spaces. 
We are glad that Professor Peirce adopts the view that the food of all 
plants consists of complex carbon compounds ; but he does not always in his 
terminology distinguish between foods and the materials out of which green 
plants may construct foods. Assimilation is very properly distinguished from 
photosynthesis. The treatment of the latter might have been somewhat 
extended with profit. It would have been especially desirable to include 
some notice of the work of Friedel (tgo1) on extracellular photosynthesis, 
especially as that work was confirmed in the autumn of 1902 by Macchiati. 
It would seem that the chapter on absorption and movement of water 
might have been advantageously placed at the beginning of the book, since 
such processes are fundamental to an understanding of respiration or nutrition. 
The discussion of absorption, transfer, secretion, etc., are in the main clear 
and in accordance with modern physical notions, though there are some slips 
that should be corrected in later editions, such as the definition of osmotic 
pressure. In the treatment of transpiration and the movement of gases, how- 
ever, the author has not freed himself from older and untenable ideas. This 
is well illustrated by the sentence: “It may easily happen in temperate 
regions that the plant takes in more water and more salts than it really needs, 
and that while the former evaporates, the latter accumulate in useless forms 
and quantities, with or without chemical change.” Similarly, the account of 
gas exchanges in the intercellular spaces is open to serious criticism. 
We fear that readers will be somewhat puzzled in the chapter on growth 
by such contradictory statements as these: “Growth is a process dependent 
upon the formation of new protoplasm” (p. 165); “The second stage in 
ee . . consists mainly, if not wholly, in the absorption of water” 
(p. 1 n page 166 we have the formation of new protoplasm and new 
cells ae as “the first and fundamental stage in the process of growth ;” 
while on page 174 we are told, “Cell division . . . . does not constitute an 
essential part of the process of growth.” 
The treatment of the subject of irritability is distinctly novel and interest- 
ing. For the student, however, it lacks a logical presentation of the phenom- 
ena of irritability which are common to all its manifestations. The chapter 
on reproduction, which in many physiological books is merely an account of - 
the morphological phenomena, is noteworthy in being almost purely physio- 
logical, and it makes very obvious how little we yet know about the physiology 
of reproduction. In this connection the author lays more stress upon the 
results of Klebs than future study is likely to justify, since Klebs omitted all 
consideration of the effects of osmotic pressure in the solutions with which 
e was working. It is not unlikely, therefore, that his conclusions will be 
profoundly modified when this factor is taken into account. Certainly the 
work of Livingston, Greeley, and others, points strongly in this direction. 
That the topic digestion is nowhere treated is certainly a noteworthy omis- 
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