466 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
A chapter on Ecology concludes a volume that brings the literature 
of the subject quite up to date. Even papers that have appeared 
since the volume was printed off find a brief notice at the end, under 
the head of Addenda. 
The 271 illustrations comprise 1,284 lettered and numbered 
figures, of which rather more than half are from original drawings by 
the author. 
No scientific library can afford to be without a copy of this work, 
which must for a number of years to come form the standard work of 
reference on the Algae of which it treats. 
" Agricultural Geology." By R. H. Rastall, M.A. 8vo. ix + 331 
pp. (University Press, Cambridge, 1916.) 10s. 6d. net. 
The title of the present book recalls another on the same subject 
published a few years ago, written by a working farmer, and the con- 
trast between the two books is a reflex of the difference between the 
points of view from which the two authors approached their subject. 
In that, the author, a professional farmer and a keen amateur 
geologist, looked at his geological facts with the eye of the agriculturist 
and sought how the problems with which he was so familiar might have 
light thrown upon them by geology. In this, the professional geologist 
states the geological facts as he conceives their bearing upon agri- 
cultural practice, but, as the preface indicates, most of his agricultural 
information has apparently been derived from books. Books, how- 
ever, do not contain the information which is so desirable. Only 
recently has any real attempt been made to correlate soil with cropping 
capabilities, and this side of the subject has received scant treatment 
here. A perusal of the book, which is an exceedingly interesting one, 
leaves one with the impression that the title has been somewhat 
ill-chosen, and that geology has less bearing upon agriculture than 
climate, aspect, and chemical and physical composition of the soil. The 
underlying rocks are of less direct importance to the farmer than 
the conditions he finds within ten inches of the surface. 
Our criticism, then, is mainly with the title. Omitting the bias 
the title gives, we find an eminently readable elementary treatise on 
geology largely in its physiographical aspects, reliable in its details, 
and suggestive to any who are thoroughly familiar with the problems 
of plant production. 
The ideal agricultural geology has yet to be written ; meanwhile 
we have the next best thing — a geology not too much concerned with 
controversial problems as to the date or age of a certain deposit, or 
with the metalliferous rocks, or even with the remarkable fossils so 
many of the rocks contain. 
' ' British-grown Timber and Timber Trees. ' ' By Angus D . Webster. 
8vo. 164 pp., with 41 plates. (Rider, London, 1916.) 5s. net. 
Mr. Webster uses the term "timber " in a very comprehensive sense. 
It means properly wood used for building, so that we are surprised to 
