SCIENCE— ADVERTISEMENTS 



The Trend of the Race 



By Samuel J. Holmes 



A study of the present tendencies in the 

 biological development of civilized mankind, 

 which makes available the latest results of 

 scientific investigation. 



396 pages, $4.00. 



Questions and Prob- 

 lems in Chemistry 



By Floyd L. Darrow 



A systematic development 

 of elementary chemistry to 

 be used with any text 

 book. 



80 Cents 



Standard Works of 

 G. Bell and Sons, London, 

 Harcourt, Brace and Co. 



X Rays and CrysteJ 

 Structure 



By Sir W. H. Bragg and 

 W. L. Bragg 



Illustrated, 



;.7S 



Rest cind Pain 



John Hilton, F.R.S. 



Twelfth edition, $3.50 



Science and Human Af- 

 fairs From the View 

 Point of Biology 



By W. C. Curtis 



Prof. Zoology, University of 

 Missouri 



A scientist's answer to the 

 evolution controversy. 



$3-50 



The Haunts of Life 



By J. Arthur Thompson 



The latest book of Prof Thompson, biologist 

 and scientist, containing his popular lectures to 

 young people before the Royal Institution of 

 Great Britain. It discusses the evolution of the 

 different types of animal life and how they 

 live and rear their young, and is intended for 

 adults as well as children. Illustrated, $2.50 



Fundamental Principles 

 of Organic Chemistry 



By Charles Moureu, Col- 

 lege de France 



Introductions by 

 Sir William Pope 



For advanced classes in 

 Organic Chemistry. 



399 pages, $2.75 



Fundaimental Conceptions 



of Psychoanalysis 



By A. A. Brill, M. D. 



An authoritative and inter- 

 esting exposition of the theory 

 and practice of psychoanalysis 

 by Freud's chief American 

 disciple. 



3-14 pages. 



!.50 



Practical Biological 

 Chemistry 



By MM. Bertrand and 

 Thomas of the Insti- 

 tute Pasteur 



Translated by H. A. 

 Colwell 



A standard work on the 

 chemical process manifested 

 by living beings upon en- 

 zymes and upon the com- 

 moner forms of fermenta- 

 tion. 



Electrons: The Nature and Properties 



of Negative Electricity 



By Sir Oliver Lodge 



Fifth Edition. $3.50 



Radium, X Rays and the Living Cell 



Hector C. Colwell 



With many plates ; some in colors, $4-50 



The Physiology of Blindness: With 



Special Reference to Color Blindness 



W. Eldridge Green, M. D. $4.50 



348 pages, $3.75. 

 (Ready in September) 



Letters of a Radio Elngineer to His Son 



By John Mills (Research Laboratories, 

 Western Electric Company) 



Letters to a real boy wdio wants to know 

 every why and how of radio from the per- 

 sonal habits of electrons to buying and in- 

 stalling the outfit. Informal but authorita- 

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Harcourt, Brace and Company 



One West Forty-seventh 

 Street, New York 



