MANUAL OE THE TREES OF NORTH AMERICA 
29 
is briefly set forth in the preface ; during the sixteen years “ eighty- 
nine species of trees and many recently distinguished varieties of 
formerly imperfectly understood species have been added to the 
silva of the United States,” and much additional information has 
been acquired in regard to geographical distribution. Bepresenta- 
tives of four families and sixteen genera which did not appear in the 
first edition are here described, which contains descriptions of 7-17 
species in 185 genera; the bulk of the volume has been increased by 
nearly a hundred pages, and the number of excellent figures has been 
augmented by 141, “ partly from drawings by Charles Edward 
Sprague, who died before his work was finished, and continued by 
Miss Mary W. Gill, of Washington.” The Manual contains the 
results of forty-four years of the author’s continuous study, “ carried 
on in every part of the United States and in many foreign countries,” 
and embodies the observations of the various botanists connected 
with the Arnold Arboretum, notably of the curator of its herbarium, 
Mr. Alfred Rehder, and of others who have travelled in various 
regions on its behalf. 
We note with interest the author’s adhesion to the Vienna Code 
of nomenclature, “ which the world, with a few American exceptions, 
has adopted ” ; and his regret that “ the confusion in the names of 
American Trees must continue as long as the Department of Agri¬ 
culture, including the Eorest Service of the United States, uses 
another and now generally unrecognised system.” 
There is no need to enter upon a detailed examination of a work 
whose reputation, as has already been said, has been so thoroughly 
established, and which, in the externals of printing and paper, is 
worthy of the contents. The absence of reference to other works, 
even to the places where the species were first published, may be 
explained by the all-suflicing completeness of the descriptive portion, 
which is rendered easily accessible by the divisions of the larger 
genera being provided with a conspectus of the species of each group. 
We note in passing that Cratcegus , which Professor Sargent has done 
so much to elaborate, now contains 153 species, as against the 132 of 
the first edition, and occupies 150 pages of text. The Manual is an 
example, only too rare, of a book which could not be better done. 
Elements of Elant Eiology. By A. G. Tansley, M.A., F.B.S., 
University Lecturer in Botany to the University of Cambridge. 
8vo, pp. 410, with G3 figs, in the text. London : Allen & Unwin. 
1922. Price 10s. 6d. 
This book is intended for medical students and others who 
desire or are obliged to obtain some elementary knowledge of plants, 
particularly in relation to general biology. It is based on the first 
part of the Elementary Biology Course at Cambridge, which has been 
framed to serve as an introduction to Biology suitable for freshmen, 
many of whom know nothing of the subject—this first portion 
occupies one term and comprises twenty-four lectures and forty-eight 
hours of practical work in the laboratory. The scope of the Cam¬ 
bridge Elementary Biology Course, as far as concerns the botanical 
portion, has increased and broadened considerably since its early days 
of the ’eighties. Then it was mainly a morphological study of repre- 
