Vol. XIII. Part I October, 1920 
BIOMETKIKA 
A JOURNAL FOR THE STATISTICAL STUDY OF 
BIOLOGICAL PROBLEMS 
FOUNDED BY 
W. F. R. WELDON, FRANCIS GALTON and KARL PEARSON 
EDITED BY 
KARL PEARSON 
o 
m 
V 
CAMBRIDGE UNIVERSITY PRESS 
C. F. CLAY, Manageb 
LONDON: FETTER LANE, E.G. 4 
also 
H. K. LEWIS AND, CO., LTD., 136, GOWER STREET, LONDON, W.0. 1 
WILLIAM -WESLEY AND SON, 28, ESSEX STREET, LONDON, W.C.2 - 
CHICAGO: UNIVERSITY OF CHICAGO PRESS 
BOMBAY, CALCUTTA AND MADRAS: MACMILLAN AND CO., LIMITED 
lOEYO: THE MABUZEN-KABUSHIEI-EAISHA 
Price Fifteeyi Shilling^ 
[Issued 18 November, 1920] 
