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. 



Editorial Committee : S. Newcomb, Mathematics ; R. S. Woodwabd, Mechanics ; E. C. Pickering, 

 Astronomy ; T. C. Mendenhall, Physics ; E. H. Thurston, Engineering ; Iea Remsen, Chem- 

 istry ; Charles D. Walcoit, Geology ; W. M. Davis, Physiography ; Henry F. Os- 

 BOBN, Paleontology; W. K. Brooks, C. Hart Meeriam, Zoology; S. H. Scudder, 

 Entomology ; C. E. Bessey, N. L. Britton, Botany ; C. S. Minot, Embry- 

 ology, Histology ; H. P. BowDiTCH, Physiology ; William H. 

 Welch, Pathology ; J. McKeen Cattell, Psychology. 



NEW SERIES. VOLUME XVII. 

 JANUAKY-JUNE, 1903. 



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NEW YORK 



THE MACMILLAN COMPANY 



1903 



