SCIENCE 
A WEEKLY JOURNAL 
DEVOTED TO THE ADVANCEMENT OF SCIENCE. 
EDITORIAL COMMITTEE: S. NEWCOMB, Mathematics; R. S. WoopwARD, Mechanics; E. C. PICKERING, 
Astronomy ; T. C. MENDENHALL, Bhysics; R. H. THURSTON, Engineering ; IRA REMSEN, Chemistry ; 
J. LE ConTE, Geology ; W. M. Davis, Physiography ; HENRY F. OsBorN, Paleontology ; W. K. 
Brooks, C. HART MERRIAM, Zoology; S. H. ScuppER, Entomology ; C. E. Brssry, N. L. 
BRITTON, Botany ; C. S. Minor, Embryology, Histology ; H. P. Bowprrcn, Physiology ; 
J. S. Bruurnes, Hygiene; J. McKEEN CATTELL, Psychology ; 
J. W. PowELL, Anthropology. 
NEW SERIES. VOLUME X. 
JULY -DECEMBER, 1899. 
NEW YORK 
THE MACMILLAN COMPANY 
1899 
