476 NATURE [jus 11; tome 
OUR BOOKSHELF. The first part of the book deals with natural 
The Hunterian Lectures on Colour-Vision and | ecu. finding itsell, itsystmuee le, with te ae 
Colour-Blindness. Delivered before the Royal 
College of Surgeons of England on February 1 
and 3, 1911, by Prof. F. W. Edridge-Green. 
Pp. 76. (London: Kegan, Paul and Co., Ltd., 
TOI14)) sonice ssodmer. 
THESE lectures are two in number, and the lecturer 
devoted the first to his views of colour-vision and 
colour-blindness, the second to the means of detect- 
ing colour-blindness from a practical point of view. 
The first lecture describes Dr. Edridge-Green’s 
explanation of colour-vision, for which he indicates 
visual purple as an essential factor. A large por- 
tion of the lecture is devoted to the visual purple 
and describes various phenomena which he has 
observed in reference to it. The “pros” are well 
given, but the “cons” are more or less absent. 
it is the latter which have led other investigators 
to reject the idea that this sensitive matter can 
fully explain the different phenomena which occur 
in colour-vision and colour-blindness. The true 
function of visual purple has to be further investi- 
gated. The part of the lecture which is devoted to 
a description of Dr. Edridge-Green’s theory of 
colour-vision has been presented to the public in 
various publications. We need scarcely sum- 
marise the theory. It is one of several theories 
which have been propounded by different investi- 
gators, and, like all, is open to criticism. 
The second lecture is devoted, as we have said, 
to the practical detection of colour-blindness. In 
it he describes the various tests which he has 
devised. The first is the lantern test. The lantern 
he describes in great detail, and informs us where 
it is to be obtained. Whether this test is efficient 
he proceeds to discuss. Then he tells us of his 
pocket wool tests, and how to use them. 
He finally gives us a description of his colour- 
perception spectrometer. This last instrument is 
ingenious, and answers the purpose for which it 
is required by the author. These lectures show 
that Dr. Edridge-Green has devoted much time 
and labour in evolving his theory. It is beside the 
mark to say whether we agree with it or not. 
Where energy is expended in scientific work, some 
step forward in furthering “natural knowledge ” 
is sure to be forthcoming, and we may prognosti- 
cate that this will be the case with the author. 
Les Sciences de la Nature en France au XVIII® 
Siécle. By Prof. D. Mornet. Un Chapitre de 
l’Histoire des Idées. Pp. x+291. (Paris: 
Armand Colin, 1911.) Price 3.50 francs. 
Tuts is a scholarly and interesting discussion of 
a remarkable period in the history of natural 
science—an almost heroic period, with Buffon as 
one of the grand figures. It is as a chapter in 
intellectual development that the author considers 
the history of natural science in France in the 
eighteenth century, but it is significant of the book 
that it continually brings us to contemplate 
science as a social phenomenon. 
NO. 2228, voL. 89] 
intrusions, its process of purification. The second 
part deals with the organisation of science; the 
third with its diffusion and triumph. A fine pic- 
ture is given of the confusion in the early 
eighteenth century, the credulity, the survivals of 
interpretation, the curiosity-collecting, the dis- 
covering of providence in nature, the nomen- 
clature ccaze, and the determined opposition 
to scientific inquiry besides. But there were men 
of thews and sinews who would not be dis- 
discouraged ; foundations were laid sword in hand, 
methods were discovered, and organisation grew 
with confidence. 
Dr. Mornet tells us eloquently of science in its 
struggle for existence and of its increasing fitness 
thereby. He shows us how spiral-like the pro- 
gress of science is, so often coming back on a 
higher turn to perennial problems, for they racked 
_their brains in the eighteenth century just as we co 
to-day, over materialism and animism, mechanism 
and vitalism, automatism and real agency. 
Repeatedly, too, he brings us to see that “la 
science porte en elle des forces qui l’ont toujours 
poussée vers la vie.” ‘The study of natural his- 
tory in the eighteenth century suffices to show 
that life and speculation yery quickly join hands.” 
The Gateways of Knowledge: An Introduction to 
the Study of the Senses. By J. A. Dell. Pp. 
xli+171. (Cambridge: University Press, 1912.) 
Price 2s. 6d. 
Mr. DEtt is a schoolmaster in a Somerset school. 
He has read about and become interested in ex- 
perimental psychology. In this book he seeks to 
interest his colleagues, and shows how boys and 
teachers may cooperate in experiments to their 
mutual advantage. It is intended, then, both for 
teacher and for pupil. The experiments have evi- 
dently been employed by the writer among his own 
pupils; they are suitable, we are told, for children 
of from twelve to fifteen years of age. 
An admirable preface is contributed by Mr. 
Hugh Richardson, from which we cannot refrain 
from quoting the following sentences: ‘ Hitherto 
the laboratory psychologist has often regarded 
the schoolmaster as too untrained and too ignorant 
to be a competent ally as an experimenter in 
mental fields. But now these studies are be- 
ginning to interest the rising generation of school- 
masters. If some of us were not so busy organ- 
ising laboratories and propagating cookery recipes 
for oxygen and chlorine, we might have leisure to 
explore the material lavished around us in the 
minds of our pupils.” 
As for the book itself, it is deserving of the 
highest praise. The text is most clearly written. 
The experiments demand the simplest apparatus 
conceivable. Exercises and problems upon the ex- 
periments are scattered through the book. There 
are chapters on the brain and sense organs, on 
touch, heat, cold, and pain, on the machinery and 
' experience of movement, on taste, smell, hearing, 
