450 BOTANICAL GAZETTE [JUNE 
known than from the originals. The topics named above are naturally those with 
which the author has chiefly concerned himself, and it cannot be said that the 
present volume contributes to general physiological literature anything new. 
The book is rather a new setting of the brilliant work and suggestive ideas of 
the author, that have previously enriched physiology, and with them is related 
the results of others in such wise as to round out the presentation. The lectures 
are readable and instructive, and they are especially commended to the attention 
of plant physiologists, who are too apt to pass over literature not strictly per- 
taining to plants.—C. R. B 
The problems of life——The third part of this book’ was issued last winter, 
and extends the author’s fundamental hypothesis to the phemonena of fertili- 
zation and heredity. To him, if one admits the premises, the difficulties of 
these phenomena fade away like morning mists. The work does not cite defi- 
nite observations, nor show, except in the most general way, how the known 
facts can be correlated by this theory; but it presents a clearly reasoned, logical 
series of deductions, which impresses the reader at once as too simple to be true. 
Moreover, one is naturally shy of a theory, which, beginning with an assump- 
tion regarding the molecular structure of protoplasm and the nature of assimi- 
lation, makes reproduction a necessary and inevitable consequence of these 
assumptions, while heredity likewise follows as a matter of course from the 
phenomena of fecundation. We were inclined to welcome the molecular con- 
ceptions of the first part,° as possibly embodying a fruitful theory, but we can- 
not follow the author as he widens and heightens his construction upon the 
acute fundamental assumption. Such inverted pyramids of logic can have no 
stability.—C. R. B 
Pfeffer’s Physiology —The third and last volume of this work was pub- 
lished about the middle of March.? It treats at length of the movements of 
plants, including the mechanical responses to various stimuli; and briefly of 
the production of heat, light, and electric tensions, and of the sources and trans- 
formations of energy. The translation, or rather the interpretation of the 
original, is of the same satisfactory character as in earlier volumes. As before, 
the editor has introduced supplementary and critical matter in footnotes; and 
in an appendix of eight pages he has supplied some important facts not men- 
tioned in the first two volumes, and a summary of the more recent literature, 
especially that connected with the present volume. Throughout, his critical 
5 GIGLIo-Tos, ERMANNO, Les problémes de la vie. IIJ¢ partie: La fécondation 
et hérédité. 8vo. pp. vili+189. Cagliari: The author, at the University. 1905. /r. 8- 
© Cf. Bot. GAZETTE 31:275. 1901. 
7 PFEFFER, W., The physiology of plants, a treatise upon the metabolism and 
and sources of energy in plants. Second fully revised edition; translated and edited 
by ALFRED J. Ewart. Volume III. Imp. 8vo. pp. viii+4sr. figs. 70. Oxford: The 
Clarendon Press. 1906. ats. 
