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NATURE 
39 

national exhibitions to the progress of industrial 
It was a marvellous display of executive 
skill and arrangement, and is well worthy of the 
closest study. Whether regarded from a constructive 
and engineering point of view, or from that of form 
and colour, the various features of the exhibition were 
endless in their variety and offered the most suggestive 
examples to the engineer, the designer, and the artist. 
A striking feature of the exhibition was the extent 
of space given to the display of facilities of education 
in Frante from the primary schools to the most 
advanced means of scientific and technical training. 
This was not confined solely to France, but other 
countries joined in it, notably the United States of 
America, which made a fine display. The exhibit 
arranged by South Kensington of gold-medal and 
other premiated works in the annual National Art 
Competitions challenged the admiration of foreign 
critics and caused the French authorities to say that 
they wondered, since such excellent designs could be 
produced, how it was that English manufacturers 
came so largely to France for designs. Another 
notable feature of the exhibition was the joint display 
of German scientific instruments. The exhibit was 
arranged collectively by ninety-eight German firms 
of instrument-makers, and was placed in charge of a 
scientific expert with qualified assistants, who undertook 
to explain and demonstrate to inquirers the purpose 
and merit of the various exhibits. Such an example of 
co-operation may be commended to the notice of the 
executive committee of the British Empire Exhibition. 
The desirability of a special display of the educa- 
tional activities of the various dominions of the Empire 
may also be suggested, such, for example, as was 
arranged with marked success for the United Kingdom 
at the Franco-British Exhibition held in London in 
Igto in a specially adapted building, which included 
a lecture hall. 
Having regard to the numerous research boards |: 
and committees for the investigation of scientific 
industrial problems under the auspices of the Depart- 
ment of Scientific and Industrial Research, the seventh 
annual report of which has lately been issued, and also 
to the existence of many separate societies for a like 
purpose, it seems appropriate that a special building 
or Hall of Science should be provided, in which lectures, 
experiments, and demonstrations illustrating many 
aspects of scientific work and discovery should be 
constantly arranged, as was done at the successful 
Scientific Novelties Exhibition just concluded at 
King’s College, London. Such provision would give a 
living interest to the exhibits and serve to stress the 
the importance of purely scientific research in the 
development of industry. 
NO. 2776, VOL. 111] 
Area of Distribution as a Measure of 
Evolutionary Age. 
Age and Area: A Study in Geographical Distribution 
and Origin of Species. By Dr. J. C. Willis. With 
chapters by Hugo de Vries, H. B. Guppy, Mrs. 
E, M. Reid, and Dr. James Small. Pp. x+259. 
(Cambridge University Press, 1922.) 145. net. 
O determine the value of Dr. Willis’s book is not 
easy. The author delivers his message with 
enthusiasm and emphasis. “Age and Area,” he 
reiterates, provides a penetrating and wholly new 
light on evolution. His supporters, four of whom 
contribute chapters to the book, endorse this opinion 
and tell us it is all right. Table after table exhibits 
special phenomena on which Dr. Willis relies. These 
tabulations seem to have been scrupulously made, and 
they certainly demonstrate some remarkable and 
novel results. The book is written with perfect 
sincerity and a conviction almost naive. Whatever 
its worth may prove to be, it is an honest attempt. 
So imposing an array must produce an effect in the 
mind even of the critical. But there are disquieting 
features. Repetition of the bald assurance that Age 
and Area is the true faith should be unnecessary. A 
judicious advocate would leave that conclusion to 
flow more quietly from the evidence. When, for 
example, we read, “ As one of our leading ecologists 
says in a letter to me, and underlines, ‘this will be 
strongly in favour of your Age and Area hypothesis,’ ”” 
we remember seeing testimonials like that elsewhere 
and in more mundane application. But though the 
reader’s scepticism is thus instantly aroused, the 
matter is worth careful attention, for to have hit on 
a new method of investigating even a part of the 
theory of evolution is no common achievement, and 
that the author has done this cannot in fairness be 
denied. 
The main idea is not difficult to grasp. It is simply 
that, subject to various provisos, the area which a 
species ‘‘ occupies” upon the earth is a measure of 
its antiquity in evolution. ‘ Occupy” is scarcely a 
fortunate word in so formal a definition. The area 
“occupied” by a species has immediately to be 
explained as meaning the area over which the species 
extends, or has extended as shown by the fossils. 
Lingula lives now in the Chesapeake and in Philippine 
waters, but to speak of it as “ occupying ”’ the whole 
world would be confusing, even though it is found fossil 
in many countries. 
A species once evolved is conceived as spreading 
in an ever-widening circle, much as a culture may do, 
inoculated upon a gelatine plate. If the medium be 
homogeneous and growth be undisturbed, the size of 
