1904] CURRENT LITERATURE 149 
an increase of tannin deposits, and a reduction in the annual ring. An impor- 
tant point is that the stomata play no particular part in the absorption of the 
injurious vapors; the whole leaf appears to be involved in the process. 
ts vary widely in their power of resistance to noxious vapors; this might 
be anticipated in the case of different plant species, but it is strongly true as well 
among different individuals of the same species. Harmful effects are accelerated 
when there is an increase of light, heat or drouth, and as might be supposed 
therefrom, one of the first signs of injury is a drying out of the leaf, due to an 
impeded circulation of water. In a similar manner, though much less fully, 
the injurious influences of other smokes and vapors are discussed, e. g., chlorin, 
hydrochloric acid, hydrofluoric acid, nitric acid, acetic acid, ammonia, hydrogen 
sulfid, bromin, tar, pyridin, phenol, fog, asphalt, illuminating gas, and dust. 
It will be seen from the list of subjects treated that the monograph considers all 
atmospheric elements apart from those which are commonly regarded as normal, 
whether or not they may be classed under the head of smokes or vapors. The 
book abounds in examples that have been taken from a wide field experience. 
For this and other reasons, the work will prove of great value to foresters, and 
to all who cultivate plants in the vicinity of cities or factories. And the botanist 
also will find here for the first time, perhaps, the injurious effects of smokes and 
Vapors presented in such a way as to permit of ready reference.—H. C. CowLes. 
Classification of flowering gases 4 
Mr. A. B. Renpie has undertaken to present to the somewhat advanced 
student “a systematic account of the flowering plants,’ and the first volume, 
now before us, comprises the gymnosperms and monocotyledons. It may be 
said that the emphasis is laid upon classification, as the title would imply, rather 
than upon morphology. The essential morphology of the great groups is out- 
lined briefly, but systematically and clearly, the modern point of view and ter- 
minology largely dominating, although it did not seem possible for the author 
to eliminate sexual terms entirely from the terminology of sporophytic structures. 
The author regrets that “the means available did not allow of the prepara- 
tion of large figures,” for this feature of the book is out of all proportion to the 
value of the text. However, he has done remarkably well with the limitations 
that were set for him. 
of the most interesting panos in the book is the first one, dealing 
with is evolution of plant classification. The subject is one which the author’s 
experience has peculiarly fitted him to treat, and this chapter is one of the best 
compact presentations of it for the general student that we have seen 
Naturally the large usefulness of the book is in its full account of ‘he plant 
8roups, in which there is brought together a mass of information that will be of 
atten 
et RENDLE, ALFRED Barton, The classification of flowering plants. Vol. I. 
~ — and Monocotyledons. 8vo. pp. xiv+403. Cambridge Biological Series. 
mbridge: The University Press. 1904. $3.50 
