< ‘Apri 21, 1923] 





























or 
these are classified under the heading of the plant 
attacked, and the chief features of each are indicated 
with reference to the further descriptions in the text, 
whereas the spraying tables summarise the applicable 
methods of treatment with instructions as to the time 
they should be carried out. Altogether the practical 
, and others, will find this a most useful handbook 
for obtaining much of the necessary information that is 
_ otherwise very scattered. 
Business Geography. By Ellsworth Huntington and 
_ Prof. F. E. Williams. With the co-operation of Prof. 
R. M. Brown and Lenox E. Chase. Pp. x+482. 
_ (New York: J. Wiley and Sons, Inc.; London: 
Chapman and Hall, Ltd., 1922.) 13s. 6d. net. 
Tue authors intend this volume to be used after 
a course on commercial and industrial geography. It 
eals with the principles of geography, the effect of specific 
graphical factors, types of human communities, and 
e trade and commerce of the continents, with more 
etailed consideration of the United States. The book 
is a welcome addition to the volumes already available 
on the geography of production and commerce, and in 
its width of outlook and wealth of ideas should prove 
very stimulating, and occasionally provocative, to all 
readers. In one essential respect it differs from most 
books on the subject: the human factor in business 
relations receives ample consideration. The world is 
eated not merely as so many places, each producing 
so many products: the varying physical and mental 
jualities of races are recognised and given their due 
eight in the explanation of the development of the 
orld. Stress is also laid on the relation of man to 
different climates in respect of wealth and efficiency. 
e book is admirably illustrated, and there are a 
number of ingenious exercises attached to each chapter. 
Tt is a book that should find wide acceptance in spite of 
its unattractive title. 
Practical Colour Photography. By E. J. Wall. Pp. 
vii+248. (Boston, Mass.: American Photographic 
Publishing Co.; London: H. Greenwood and Co., 
Ltd., 1922.) 135. 3d. 
‘THE representation of colour, in addition to form and 
light and shade, by photographic means is a subject 
that has been allowed to get very far behindhand so 
far as text-books of photography are concerned. Mr. 
Wall’s volume is therefore very welcome as doing a 
t deal towards filling this gap in photographic 
iterature, which has been automatically increasing for 
many years. It does not quite fill the gap, for photo- 
‘mechanical methods are not treated of, historical and 
theoretical data have been, so far as possible, omitted, 
and the scope of the work has been restricted by the 
fact that all methods and formule given have been 
personally tested in practice. But within the limits 
indicated it is surprising how many methods there are 
_ of representing colour. Of three-colour processes there 
are the carbon and gum bichromate processes, the im- 
bibition of dyes, mordanting processes, the bleach-out 
process, and the use of screen plates (autochrome, 
Paget). Of what may be called direct processes there 
are the interference heliochromy of Lippmann, the use 
of “silver subchlorides,” and the diffraction and pris- 
matic dispersion processes. Finally there are two- 
NO. 2790, VOL. 11 | 
NATURE 

531 
colour processes, and those adapted specially for cine- 
matography. The book forms an excellent practical 
introduction to the subject. 

Le Négatif en photographie. Par A, Seyewetz. Deux- 
iéme édition, revue, corrigée et augmentée. (En- 
cyclopédie scientifique: Bibliothéque de Photo- 
graphie.) Pp. viii+308. (Paris: Gaston Doin, 
1923.) 15:40 francs. 
M. SEYEWETz is chiefly known to us by the researches 
that he has carried out, often in conjunction with M. 
M. Lumiére. One naturally expects an author to treat 
more fully of those subjects that he has personally 
Studied. In the present case this is a distinct recom- 
mendation, for the author’s investigations have been 
so largely connected with the processes involved in 
negative making. The summaries of the characters, 
use, and effects of the various developing agents are 
especially valuable. It is of interest to notice that M. 
Seyewetz is not one of those who believe that develop- 
ment is a mechanical process which cannot be varied 
except to the detriment of the negative. The paper 
and the quality of the illustrations of this volume show 
that our neighbours have not recovered so far as we 
have in this country from the detrimental effects of the 
War, but these matters do not detract from the sterling 
character of the volume. 
Practical Handbook on the Diseases of Children: For 
the Use of Practitioners and Senior Students. By Dr. 
Bernard Myers. (Lewis’s Practical Series.) Pp. 
xvi+ 548. (London: H. K. Lewis and Co., Ltd., 
1922.) 21s. net. 
THE important subject of diseases of children is one 
which is too often neglected in the curriculum of the 
medical student. Dr. Bernard Myers has produced a 
handbook in which he has treated the subject mainly 
from the practical side. He has adopted the usual 
arrangement of considering anatomy and physiology 
first, then clinical investigations and the diseases of the 
various systems. Articles have been contributed by 
experts in their special branches, e.g. biochemistry, 
serum therapy, physiology of digestion, and syphilis. 
Some confusion may arise from the separation of 
nutritional disturbances from affections of the stomach 
and intestine, and also from the classification of nutri- 
tional disturbances as “ failure to gain,” ‘“‘ dyspepsia,” 
“ decomposition,” and “ intoxication.” 
The moderate size of the book, its concise descrip- 
tions and practical aspect, combine to make it a useful 
addition to the student’s text-books and the practi- 
tioner’s library. 
Religion and Biology. By Ernest E. Unwin. (Christian 
Revolution Series, No. 15, Pp. 185.) (London: 
The Swarthmore Press, Ltd.; New York: George 
H. Doran Co., 1922.) 6s, net. 
TuIs work, written from the point of view of a member 
of the Society of Friends, is an attempt to outline the 
biological approach to questions of religious thought, 
and should be of use to school teachers. The author 
believes he has a message for biologist and school- 
masters. His gentle and spiritual point of view never 
raises opposition, and the book will be found of value 
for the purpose for which it is designed. 
