SCIENCE 



A WEEKLY JOURNAL 



DEVOTED TO THE ADVANCEMENT OF SCIENCE 



Editorial Committee : S. Newcomb, Mathematics ; R. S. 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 Meeriam, Zoology ; S. H. Scudder, Entomology ; C. E. Bessey, 



N. L. Beitton, Botany ; C. S. Minot, Embryology, Histology ; H. P. Bowditch, 



Physiology ; J. S. Billings, Hygiene ; William H. Welch, Pathology ; 



J. McKeen Cattell, Psychology ; J. W. Powell, Anthropology. 



NEW SEEIES. VOLUME XII. 

 JULY -DECEMBER, 1900. 



NEW YORK 



THE MACMILLAN COMPANY 



1900 



