SCIENCE 



A WEEKLY JOURNAL DEVOTED TO THE ADVANCEMENT OF SCIENCE, PUBLISH- 

 ING THE OFFICIAL NOTICES AND PROCEEDINGS OF THE AMERICAN 

 ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 



EoiTOBiAL CoMMiTTKK : S. Nkwcomb, Mathematics; K. S. Woodwaed, Meobanioe ; E. C. Pickkeing, 



Astronomy ; T. C Mbndknhall, Physios ; Ika Rbusen, Chemistry ; Chaelbs D. Walcott, 



Geology ; W. M. Davis, Physiography ; Hbney F. Osboen, Paleontology ; W. K. 



Bbooes, C. Haet Meeeiam, Zoology ; S. H. Scuddeb, Entomology ; C. E. 



BEaasY, N. L. Bbitton, Botany ; C. S. Minot, Embryology, Histology ; 



H. P. BowDiTCH, Physiology ; William H. Welch, 



Pathology ; J. McKeen Cattell, Psychology. 



NEW SERIES. VOLUME XVIII. 

 JULY- DECEMBER, 1903. 



NEW YORK 



THE M1.CMILLAN COMPANY 



1903 



