1912] "CURRENT LITERATURE 353 
In the chapter on “‘The organic constituents of the soil solution” is given 
a convincing account of the toxic substance theory of soil fertility. Any treat- 
ment of an organically poisoned soil, which will increase its absorptive prop- 
erties or its oxidizing power seems to have a beneficial effect upon plants grow- 
ing therein. The commonly used fertilizer salts are often effective in this way, 
so that there is nothing in the new theory which might lead one not to use the 
ordinary fertilizers nieaiet by the “plant food” theory. This more recent 
finding of the Bureau of Soils makes the violent and often personal attacks, 
that have been calculated to hinder the progress of these investigations, 
appear largely as the mere pommelling of a man of straw 
The book ends with a chapter on the phenomena of alkali soils, dealing 
with the development of alkali and the theory of its practical handling — 
B. E. Livrncston: 
Fossil plants 
In the second volume of his Fossil planis, Professor SewARpD* continues the 
work begun over ten years ago and apparently destined to become truly monu- 
mental. It is to be hoped that his anticipation of the early appearance of the 
third volume on the gymnosperms may be realized, and that a fourth hinted 
at, rather than promised, which is to deal with the angiosperms, may likewise 
soon be published. The author brings very unusual qualifications to the titanic 
task of writing a comprehensive textbook of the present condition of our 
knowledge of fossil plants in both their botanical and geological bearings. 
He possesses in an unusual degree an acquaintance with the older paleobotany, 
dealing mainly with the superficial features of plants as seen in impressions, and 
at the same time is thoroughly in touch with the modern development of the 
subject, which has put the study of internal structure in the foreground. It 
is to be regretted that some of the younger investigators of fossil plants are 
often deplorably ignorant of the older point of view. SEWARD certainly does 
not err in the direction of the neglect of the older literature or superficial 
features, which in many cases constitute the only evidence available. Another 
advantage enjoyed by the author is his unique first-hand knowledge of the 
material treated. By his travels to various paleobotanically interesting 
regions and by personal visits to most of the important European collections, 
he has acquired an intimate acquaintance with fossil plants in their full 
systematic, geological, geographical, and evolutionary bearings possessed by no 
other living paleobotanist. 
The present volume continues the treatment of the Pteridophyta begun in 
the first, which appeared over ten years ago. In the preface he points out the 
happy circumstance that recent activity has been chiefly in the field of the pres- 
ent volume, and that as a consequence the first is little out of date. Beginning 
with a continued discussion of the Sphenophyllales, the writer subscribes a very 
SEWARD, A. C., Fossil ~~ Vol. II. pp. xxii+624. figs. 265. Cambridge: 
The Paliniaies Press. 1910 
