662 
neglected by the traveller and amateur ethnographer, 
and even by the specialist, which promises, however, 
to yield results of some importance, For I have no 
doubt that my confirmation of Sir James’s theories from 
a limited ethnographical area will be followed by other 
more important discoveries all the world over. 
Thus the Golden Bough, far from being a classic in the 
sense of having attained the fulness of its glory and de- 
serving honourable rest, isa book which still has some 
hard service in the field before it, a book which should 
be n the kitbag of every ethnographic explorer. A 
modern ethnographer, in his researches among savages, 
must, while making his observations, remain still in con- 
tact with theoretical literature in order to receive from 
it constant inspiration and guidance, especially if he is 
bent on doing intensive field-work, if he is willing and 
able to remain for months and years among the same 
tribe and study it by means of their own language and 
by personally taking part in the tribal life. In such 
study I derived constant inspiration and benefit from 
the works of Westermarck, Karl Biicher, Ratzel, 
Marett, Hubert and Mauss, Crawley and Rivers, some of 
which I actually have re-read while in the field, others 
again in the intervals between my expeditions. Alas! 
at that time the twelve volumes of the Golden 
Bough were too heavy and costly a burden to carry 
across sago swamps, to paddle over lagoons in an out- 
rigger always ready to capsize, or to keep in a tent or 
thatched hut by no means rain- and insect-proof. Now 
the more fortunate field-worker can easily take with 
him, handle, and constantly refer to the new, one- 
volume, abridged edition. 
To the student in his library, this abridged edition 
will no doubt only serve as a handy guide, as a sort of 
explicit digest, or to the beginner as a preliminary 
introduction. The full version is indispensable to the 
student, and it is also the most fascinating and instruc- 
tive reading to the layman. But no doubt many a one 
who was at first shy of tackling directly the Golden 
Bough will, in the short edition, find a bridge to the 
full work, which is not only the most important achieve- 
ment of Sir James Frazer, but also the last word of 
modern anthropological scholarship. 
B. MA.LINowskKI. 

Modern Cosmogony. 
The Nebular Hypothesis and Modern Cosmogony : 
being the Halley Lecture delivered on May 23, 1922. 
By J. H. Jeans. Pp. 31+4 plates. (Oxford : 
Clarendon Press; London: Oxford University 
Press, 1923.) 25. 6d. net. 
R. JEANS’S analysis of the modes of rupture 
of fluid masses under the influence of excessive 
rotation or of the gravitation of other bodies, earned 
NO. 2794, VOL. 111] 
NATURE 
aN eee 
[May 19, 1923 
him the Adams prize of the University of Cambridge 
in 1917 and the gold medal of the Royal Astronomical 
Society in 1921. The results appeared in his “ Prob- 
lems of Cosmogony and Stellar Dynamics,” published 
in z919. The relation between his book and the 
pamphlet under review is that while the book was a 
theoretical work with an observational commentary, 
the Halley lecture is an account of observations with a 
theoretical commentary. 
The Laplace-Roche theory of the development of a 
rotating and condensing gaseous mass showed that it 
would be flattened at the poles, and, if strongly con- 
densed towards the centre, it would ultimately become 
lenticular, with a sharp edge. The next stage was 
believed to be that this edge would open all round, and 
the matter would pour out to form a ring. The rings 
of Saturn were claimed as an example of this process, 
but it is now known that they could never have passed 
from the gaseous to the solid state if they had been 
first produced in this way at their actual distance from 
the planet. The heavens have been searched for other 
bodies showing rings of Laplacian type, but none has 
been found. 
Numerous nebulz, however, show the flattened and 
lenticular forms indicated by the early stages of the 
theory, and Jeans considers that they are true examples 
of it. Other nebule show lenticular centres, with 
definite indications of detached matter around the 
equatorial sharp edge, and the more of this matter 
there is, the clearer does it become that it is not in the 
form of a ring or series of rings, but of spiral arms. In 
fact, known nebule afford examples of every inter- 
mediate stage, from the flattened symmetrical mass, 
through the lenticular form, to the typical spiral nebula, 
“and it is difficult to resist the conclusion that this 
gradation corresponds to an actual course of evolution. 
This evidence is beautifully presented in the published 
lecture. 
Although the astronomical evidence for such a 
phenomenon is strong, it calls for a dynamical explana- 
tion. We need to know why the matter is ejected 
almost entirely at two opposite points and not uniformly 
all around the equator. Jeans suggests, with much 
plausibility, that the equator would be distorted by 
the gravitation of surrounding bodies, and that, how- 
ever small the distortion was, it would suffice to localise 
the ejection at two opposite points, and hence two arms 
would be formed instead of a ring. 
Van Maanen, at Mount Wilson, has measured the 
motions of identifiable parts of spiral nebule. The 
motion is curious. The arms are approximately 
equiangular spirals, and the matter constituting them 
is moving outwards along the arms, its velocity in- 
creasing the farther it recedes from the nucleus. The 
