276 THE JOURNAL OF BOTANY 
dence of the connection between the phenomena of plant-affinities 
and plant- associations, between mutual relationships and ecological 
conditions ; but there is forced upon the observer the correlation of 
parallel processes, in the modification of the plant-type inherent in 
itself” age the inconstant conditions of environment. 
1e order of immutability of species and permanent fixity 
of type is pidastied away, superseded by the new order based on the 
Theory of Descent, not indeed in an unbroken succession of fotiidhe 
for many groups lie quite off the line of normal development, but 
evolving with ever-varying cniceeisheoor from within, and with 
ever-widening adaptation from withou 
i Bini N. WIitutams. 
The Student's Handbook of British Mosses. By H, N. Dixon, M.A., 
F.L.S.; with illustrations and keys to the Genera and Species 
H.G. Jameson, M.A. Second Edition, revised and enlarged. 
1904. Pp. 635; Bt ‘re 65. Maia Wheldon, Great Queen 
Street. 18s. 6d. net. 
In this volume the Pe has within his reach, at a price “9 
than half that of Wilson’s Bryologia Britannica, a work as able 
its descriptions and as faithfuli 
manual. The influence of the first edition was so far reaching, i. 
new moss students sprang up in every part of the United Sayre 
thus our knowledge of the distribution of these plants has widely 
increased, and so many new species and varieties have “in added 
to our flora, that a new edition has been called for in less than eight 
y he great success of the work is due to the fact that the 
author has the power of ~ ga ie in simple language all he has to 
tell us about these plants. The expladatory notes (in the style of 
ose in Wilson’s cecal Bryologia) given with every species, tlie 
aig of the descriptions, together with the printing in different 
e the more nai characters of each species or variety, are great 
a to the student. To the beginner the numerous illustrations 
will specially appeal; these, if used with the keys to the genera and 
species, nt be found of greatest value 
opens with an introduction, in which we have a very 
able and Incid account of the general characteristics of mosses, their 
vegetative and reproductive organs; this is illustrated by five plates 
with more than a hundred figures, showing the differences in mode 
of growth, in stem, leaf, and cell structure ; the forms of the fruit, 
with its appendages, of the peristome, and the inflorescence ; and 
the student who has studied the infcodmotion, which is written in 
an interesting style, will find himself in a position to begin the 
seriou s study of mosses. This is followed by a glossary of some 
eight oui in which the terms used in the work are fully explained. 
Then comes an able Mihnctotis key to the genera, similar in ar- 
rangement to that given by Bentham in his Handbook, and quite as 
helpful; this, if carefully used, will enable the veriest tyro to find 
out ote genus of any plant he studies. Having worked out the 
genus, he will find in the keys to “the species still further help to 
