CONTENTS 
Page 
Mathematics. — Conjugate Systems of Space Curves with Equal Laplace- 
Darboux Invariants By E. J. Wilczynski 59 
Mathematics. — Transformation of Surfaces . . . By L. P. Eisenhart 62 
Chemistry. — Potassium Ammono Argenate, Barate, Calciate, and Sodate 
By Edward C. Franklin ' 65 
Chemistry. — Metallic Salts of Ammono Acids . By Edward C. Franklin 68 
Chemistry. — Ammonobasic Iodides of Aluminium . By Edward C. Franklin 70 
Chemistry. — A Revision of the Atomic Weight op Lead: The Analysis of 
Lead Bromide and Chloride 
. By Gregory Paul Baxter, Fred Leslie Grover and Thorbergur Thorvaldson 71 
Chemistry. — A Revision of the Atomic Weight op Praseodymium 
By Gregory Paul Baxter and Olus Jesse Stewart 77 
Geophysics. — On the Earth Considered as a Heat Engine By George F. Becker 81 
Botany. — A Phylogenetic Study of Cycads . .By Charles J, Chamberlain 86 
Zoology. — Dimorphism in Size of Spermatozoa and its Relation to the 
Chromosomes By Charles Zeleny and E. C. Faust 91 
Genetics. — An Interpretation op Self-Sterility . . .ByE.M. East 95 
Physiology.— The Basal Caloric Output of Vegetarians as Compared 
WITH THAT OF NoN-VeGETARIANS OF LiKE WeIGHT AND HeIGHT . 
By Francis G. Benedict and Paul Roth 100 
Physiology. — The Influence of Athletic Training Upon Basal Metabo- 
lism By Francis G. Benedict and H. Monmouth Smith 102 
Physiology.— A Comparison of the Basal Metabolism of Normal Men 
AND Women By Francis G. Benedict and L. E. Emmes 104 
Physiology. — The Factors Affecting Normal Basal Metabolism 
By Francis G. Benedict 105 
Physiology. — On the Nature of the Nerve Impulse . By Shiro Tashiro 110 
Psychology. — A Point Scale for Measuring Mental Ability 
. . . By Robert M. Yerkes 114 
Psychology. — Color Vision in the Ring-Dove (Tutur risorius) . 
By Robert M. Yerkes 117 
Genetics.— The Feebly Inhibited. II. Nomadism or the Wandering Impulse 
with Special Reference to Heredity . . . By C. B. Davenport 120 
Announcements.— W. E. Hale Lectures . . . . . . . .122 
