SCIENCE 



A WEEKLY JOURNAL 



DEVOTED TO THE ADVANCEMENT OF SCIENCE. 



Editorial Committee : S. Newcomb, Mathematics ; K. S. Woodward, Mechanics ; E. C. Pickering, 



Astronomy ; T. C. Mendenhall, Physics ; E. H. Thurstos", Engineering ; Ira Remsen, Chemistry ; 



J. 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 ; J. McKeen Cattell, Psychology ; Daniel G. Brin- 



ton, J. W. Powell, Anthropology. 



NEW SERIES. VOLUME IX. 



JANUARY -JUNE, 1899. 



NEW YORK 



THE MACMILLAN COMPANY 



1899 



