SCIENCE 
A WEEKLY JOURNAL DEVOTED TO THE ADVANGEMENT OF SCIENCE, PUBLISH- 
ING THE OFFICIAL NOTICES AND PROCEEDINGS OF THE AMERICAN 
ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 
EDITORIAL COMMITTEE: S. NEwcomB, Mathematics; R. 8. WooDWARD, Mechanics; E. C. PICKERING, 
Astronomy ; T. C. MENDENHALL, Physics; R. H. THURSTON, Engineering ; IRA REMSEN, Chemistry ; 
JosEPH LE ConTE, Geology ; W. M. DAvis, Physiography ; HENRY F. OSBORN, Paleontology ; 
W. K. Brooks, C. HART MERRIAM, Zoology ; 8. H. ScuDDER, Entomology ; C. E. BESSEY, 
N. L. Brirron, Botany; C. S. Minor, Embryology, Histology ; H. P. BownpitTcH, 
Physiology; J. S. Brunines, Hygiene; WILLIAM H. WELCH, Pathology ; 
J. MCKEEN CATTELL, Psychology ; J. W. POWELL, Anthropology. 
NEW SERIES. VOLUME XIII. 
JANUARY-JUNE, 1901. 
NEW YORK 
THE MACMILLAN COMPANY 
1901 
