Thoughts on the Teaching and Practice of Medicine.

Thoughts on the Teaching and Practice of Medicine: PROFESSOR W. S. THAYER. ......................................... 349 A System of "Definitive Units" proposed for Universal Use: DR. GEORGE A. CAMPBELL .............................. 353 The American Association for the Advancement of Science: Associated Organizations: DR. BURTON LIviNGSTON....... ; 357 Scientific Events: Expedition of the California Academy of Sciences to the Bevillagigedo Islands; Fellowships in Cooperation with the Bureau of Mines; The Research Club of the University of Michigan; The American Chemical Society ............... ........................... 359 Scientific Notes and News ................... ....................... 361 Universityand Educational Notes ........................................... 365 Discussion and Correspondence: Method of Measuring Deep Sea Tides: PROFESSOR R. W. WOOD. Observations of Shadow Bands: PROFESSOR S. A. MITCHELL. The Segregation of Physical Geography: DR. F. A. CARLSON. Microsporidia: ROKSABRO KuDO. Is Our Plan of Meetings the best possible?: M. C. MERRILL .................. 365 Evolution in Education in California .................................... 367 Scientiflc Apparatus and Laboratory Methods: A Simple Membrane Manometer: PROFESSOR ARTHUR D. HIRSCHFELDER AND RAYMOND L. GREGORY ......................................... 368 Special Articles: Tree Trunks, Growth and Reversible Variations in Circumference: DR. D. T. MACDOUGAL. The Purification of Zirconium: DOROTHY HALL BROPHY.......... 370 Science New:........ x