

June 2, 1923] 
NATURE 
735 

as section on two of its planes of symmetry, while 
its faces are isosceles triangles. He claims that this 
figure lends itself better than the regular tetrahedron 
to the construction of models representing the structure 
of organic compounds. The close packing of poly- 
hedral figures is an important factor in crystallographic 
research, but, when it is not correlated in any way 
with crystallographic data, it cannot be regarded as 
of any value in the investigation of molecular structure. 
The author proceeds as if the carbon atoms were 
actually tetrahedral in shape, with real poles at the 
corners, whereas in fact, the tetrahedron merely serves 
as a convenient means of showing the directions in 
which the valencies radiate. It is, however, interesting 
to notice that the figure which Lewis obtained by con- 
centrating four duplets on the centres of four edges 
of a cube is actually a tetrahedron of the shape 
described by the author, although obviously the 
duplets in marsh gas must occupy the alternate corners 
of a cube, since all the evidence points to the fact 
that methane has the full symmetry of a regular | 
tetrahedron. 
The Trend of Evolution. 
The Evolution of Man: a Series of Lectures delivered 
before the Yale Chapter of the Sigma Xi during the 
Academic Year 1921-1922, by Richard Swann Lull, 
Harry Burr Ferris, George Howard Parker, James 
Rowland Angell, Albert Galloway Keller, Edwin Grant 
Conklin. Edited by George Alfred Baitsell. Pp. 
x+202. (New Haven: Yale University Press; 
London : Oxford University Press, 1922.) 
N the chapter entitled “The Natural History of 
Man” Prof. Ferris gives a very lucid summary 
of the most elementary facts of embryology and 
anatomy, which suggests to the uninitiated reviewer 
that the Society of the Sigma Xi, for whom the lectures 
in this book were prepared, is a lay body unfamiliar 
with biological teaching. As a means of interesting 
such an audience in some of the manifold aspects of 
biology and sociology these lectures no doubt served 
a useful purpose, but why call the volume “ The 
Evolution of Man”? One would imagine that in 
a series of six lectures with such a title some one 
would have discussed seriously the problems of man’s 
pedigree, and have attempted to explain how and 
why the human family acquired those distinctive 
attributes of brain and mind which conferred the 
rank of mankind upon it. But there nothing of the 
kind is to be found in the book. 
Prof. Parker gives an excellent account of his in- 
vestigations on the nervous system of sponges ‘and 
other animals, but the title ‘The Evolution of the 
NO. 2796, VOL. 111 | 
15s. net. 
Nervous System of Man” raises hopes that are not 
fulfilled ; and the same remark applies to the address 
by the president of Yale on “The Evolution of In- 
telligence,” as well as to Prof. Keller’s “ Societal 
Evolution.” The criticism one is impelled to make 
of all these addresses is that, while they are interesting 
and illuminating, both their own titles as well as that 
of the book are irrelevant. 
In Prof. Conklin’s essay, the title of which the 
reviewer has adopted as the label for this notice, 
is a sane discussion of the trends of civilised mankind 
under post-War conditions and an earnest plea for 
education, and better education, as the remedy for 
the ills of society and the means of averting the down- 
fall of the best types of mankind. 

Our Bookshelf. 
Department of Agriculture and Technical Instruction for 
Ireland. Memoirs of the Geological Survey of Ireland. 
Mineral Resources. Memoir and Map of Localities 
of Minerals of Economic Importance and Metalliferous 
Mines in Ireland. By Prof.G. A. J. Cole. Pp. 155. 
(Dublin: Stationery Office, 1922). 7s. 6d. net. 
Ir is much to be regretted that this volume must be 
looked upon as the swan-song of the old regime in 
Ireland rather than as the first effort of the new 
authorities. Information as to the mineral resources 
‘of Ireland has never before been collected into any 
authoritative memoir, but had to be sought for piece- 
-meal among a number of miscellaneous geological and 
‘mining publications, for, as the author of the present 
work correctly observes, Sir Robert Kane’s book on the 
industrial resources of Ireland is now far too old to be 
‘of any real value under the economic conditions of the 
present day. 
Prof. Cole has done his work extremely well ; he has 
arranged the various minerals that Ireland produces in 
alphabetical order, commencing with antimony and 
ending with zinc. 
It is perhaps characteristic of an 
Irish publication that the most important of all mineral 
products, namely coal, is not even mentioned. The 
author states specifically that he excludes sands, clay, 
and marble, and devotes his attention to ‘‘ minerals of 
economic importance ”’ ; surely coal should be included 
under this head. The other minerals of economic 
‘importance are very fully and clearly dealt with ; the 
list of localities is very complete and carefully drawn 
up, and all the more important occurrences are briefly 
described. If it does nothing else, the present work will 
serve to dispel some of the wild statements that are 
occasionally heard as to the immense mineral resources 
of Ireland, which have been neglected or, it is even 
«sometimes hinted, deliberately concealed, by jealous 
Englishmen. Among the more persistent of such 
legends is that of the immense resources of iron ore in 
the Arigna valley ; the present work shows that two 
persevering attempts were made to found an iron 
industry there, at the end of the eighteenth and again 
in the first half of the nineteenth century, and that both 
ended in failure ; at what appears to have been the last 
