CONTENTS. 



Page. 

 I. New or Critical Species of Chiionomyces and Rickia. By Roland 



Thaxter 1 



II. The Velocity of Polymorphic Changes between Solids. By P. W. 



Bridgman 55 



III. Polymorphism at High Pressures. By P. W. Bridgman ... 89 



I\'. Theoretical Investigation of the Radiation Characteristics of an 



Antenna. By G. W. Pierce 189 



V. The 'Refractive Body' and the 'Mitochondria' of Ascaris canis 



Werner. By A. C. Walton 253 



VI. Differential Geometry of Two Dimensional Surfacefi in Hyperspace. 



By E. B. Wilson and C. L. E. Moore 267 



VII. A Classification of Quadratic Vectors. By F. L. Hitchcock 369 



VIII. The Mountain Ants of western North America. By W. M. 



Wheeler 455 



IX. The Electrical Resistance of Metals under Pressure. By P. W. 



Bridgman *. 571 



X. New Laboulbeniales, chiefly Dipterophilous American Species. 



By Roland Thaxter 647 



XI. On the Pigmentation of a Poly clad. By W. J. Crozier . . . 723 



XII. The Joule-Thomson Effect in Superheated Steam: — 1. Experi- 

 mental Study of Heat-leakage. By H. M. Trtjeblood . . . 731 



XIII. Records of Meetings 807 



Biographical Notices 826 



Officers and Committees for 1917-18 879 



List of Fellows and Foreign Honorary Members 881 



Statutes and Standing Votes 899 



RuMFORD Premium 913 



Index 915 



