Vol. XIII. Parts II and III 
July, 1921 
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 
CAMBRIDGE UNIVERSITY PRESS 
C. F. CLAY, Manager 
LONDON: FETTER LANE, E.G. 4 
it also 
H. K. LEWIS AND CO., LTD., 136, GOWER STREET, r.ONDON, W.C. 1 
WHELDON AND WESLEV, LTD., 28, ESSEX STREET, LONDON,' W.0.2 
CHICAGO: DSIVEBSITY OF CHICAGO PRESS 
(AGENTS FOR THE UNITED STATES AND CANADA) 
BOMBAY, CALCUTTA AND MADRAS; MACMILLAN AND CO., LIMITED 
TOKYO: THE MAIIUZEN-KABUSHIKI-KAISHA 
Price Twenty-jive Shillings 
{Issued 16 July, 1921] 
