JuLy 7, 1899. ] 
the right 52%, the left 36%. (2) In both 
right- and left-handed lunging, the body 
had gained in grace and coordination of 
movement. (3) The probable errors of both 
hands had been markedly decreased as the 
result of the practice of the right hand. 
Cross-education may be the result chiefly 
of changes wrought in the central nervous 
system. In the tapping, in which a mini- 
mum of muscular strength is required, the 
gain is about equal on both sides. In the 
test of strength a smaller proportional gain 
was found in the side not practiced. The 
transference of peripheral effects cannot 
be ignored altogether, since in the dumb- 
bell test there was a decided increase in the 
girth of the arm not practiced, and in its 
power to resist fatigue. 
The facts may be explained as the result 
of two factors: (1) the close nervous con- 
nection, through motor centers, between 
symmetrical muscle groups on opposite 
sides of the body and between groups re- 
lated in function or position ; (2) the de- 
velopment of general will power and atten- 
tion, through the practice of one form of 
volition. 
Water W. Davis. 
PSYCHOLOGICAL LABORATORY, 
YALE UNIVERSITY, NEw HAVEN, Conn. 
SCIENTIFIC BOOKS. 
The History of Mankind. By FRIEDRICH RATZEL. 
Translated from the second German edition 
by A. J. Butter, M.A. With introduction 
by E. B. Tytor, D.C.L., F.R.8. London, 
Macmillan & Co. 1898. Colored plates, maps 
and illustrations. Volume III. 8vo. Pp. 599. 
The first edition of Ratzel’s ‘ Vélkerkunde,’ 
which has been in our libraries for ten years, 
is divided into three substantial parts or vol- 
umes, the third of which is taken up with the 
more cultured peoples that are outside of the 
age of steel and steam. For some reason or 
other, the order of the work has been changed 
in the English edition. The higher American 
peoples are thrust out; Africa obtrudes itself into 
’ SCIENCE. 
21 
Volume III., so that it really commences on 
page 149. It is with the remaining pages that 
we have here to deal. 
The proper appreciation of this volume and, 
indeed, of the whole work, demands of the 
reader familiarity with his Peschel, Friedrich 
Miller, Brinton and Keane, and he would do 
well to have near by aset of Standford’s Com- 
pendiums. It is nota treatise on ethnology— 
the work would be vastly improved by a few 
tables showing the connection and affiliation of 
peoples —but a discussion of human artificialities 
in relation to certain culture areas. 
The eastern hemisphere presents to the stu- 
dent a number of arenas on which the drama 
of mankind has been enacted. On these, races 
come and go, but Nature’s life repeats itself 
and the forces of progress and reaction are im- 
perceptibly active in them. 
In speaking of this play of culture-influences 
between Africa and Asia the author develops 
the Erythrzan, or Red Sea group of peoples. In 
contrast with Dr. Brinton’s emphasis upon the 
Hamite and West African forces, Ratzel looks 
eastward for the predominating influences. 
The arena for the sharp conflict between 
nomad pastorals and settled tillers is found in 
a broad strip of territory extending diagonally 
from 10° to 60° north latitude and from the At- 
lantic to the Pacific. 
India is for the author a region where races 
have been broken up, pulverized and kneaded 
by conquerors. Doubtless a pre-Dravidian ne- 
groid type came first, of low stature and mean 
physique, though these same are, in India, 
also the result of poor social and economic 
conditions. Dravidians succeeded negroids, and 
there may have been Malay intrusions, but 
Australian affinities are denied. Then suc- 
ceeded Aryan and Mongol, forming the present 
pot pourri through conquest and blending. 
Northward of India, as suggested, the settled 
Iranian and the nomad Mongol furnish to the 
author the best opportunity to study and de- 
velop the thought ever dominant in his mind. 
In the history of mankind the lots fall diversely, 
but to each race its task is assigned, and none is 
left without opportunity of casting its threads 
into the great fabric. 
In southeastern Asia, Ratzel sees a great 
