CONTENTS. 



Page. 



I. /. On Tropical American Compositae, chiefly Eupatorieae. 



II. A Recension of the Eupatoriums of Paree. By B. L. Robin- 

 son 1 



II. A Step Forward in the Methodology of Natural Science {an Introduc- 

 tion to: The Functional Relation of one Variable to each of a 

 Number of correlated Variables determined by a Method of Suc- 

 cessive Approximation to Group Averages. By George F. 

 McEwen and Ellis L. Michael.) By Wm. E. Ritter ... 89 



III. Contribution to the General Kinetics of Material Transformations. 



By Alfred J. Lotka 135 



IV. Rotations in Space of Even Dimensions. By H. B. Phillips and 



C. L. E. Moore 155 



V. Orbits resulting from Assumed Laws of Motion. By Arthur 



Searle 189 



VI. New Dimorphomyceteae. By Roland Thaxter 209 



VII. Some Geometric Investigations on the General Problem of Dynamics. 



By Joseph Lipka 283 



VIII. Specific Heat of Ammonia. By H. A. Babcock 323 



IX. A Monograph of the American Frogs of the Genv,s Rana. By G. A. 



BOULENGER 411 



X. Records of Meetings . 481 



Biographical Notices 505 



Officers and Committees for 1920-21 519 



List of Fellows and Foreign Honorary Members 520 



Statutes and Standing Votes 539 



Rumford Premium 555 



Index 556 



\lolO^ 



