SCIENCE— ADVERTISEMENTS 



A Synopsis of the 



Aphididae of California 



By ALBERT F. SWAIN 



22t pages. J7 places. Paper, $2.25 



Other Recent Publications 

 Calendars of the Indians riorth ,of Mexico, by Leona 



Cope -■,••; S -75 



The Effect of Several Types of Irrigration Water on 

 the Ph Value and Freezing: Point Depression of 

 Various Types of Soils, by D. R. Hoagland and 

 A. W. Christie 20 



Notes on the Natural History of the Bushy- tailed Wood 



Rats of California, by Joseph Dixon 25 



Geology of a Part of the Santa Ynez River District, 



Santa Barbara County, Cal.. by Wm. S. W. Kew .25 



The Marine Algae of the Pacific Coast of North Amer- 

 ica, Part I. Myxophyceae, by William A. Set- 

 chell and Nathaniel l/yon Gardner 1.50 



The University of California Press 



Berkeley, California 280 Madison Ave, New York 



BLAKISTON 



PALLADIN - LIVINGSTON. Plant 

 Physiology. Authorized English Edition 

 Based on the German Translation of 6th 

 Russian Edition and on 7th Russian Edition. 

 173 Illustrations. 



8vo. XXV -f 320 pp. Cloth, $3.00 Postpaid. 

 By V. I. Pahadin, Professor in the Uni- 

 versity of Petrograd. Edited by Burton 

 Edward Livingston, Ph.D., Professor of 

 Plant Physiology and JDirector of Laboratory 

 of Plant Physiology, fohns Hopkins Univ. 



HARSHBERGER. A Text-book of 

 Mycology and Plant Pathology. 271 Illus- 

 trations. 



12mo; xiii+779 pp. Cloth, $3.00 Postpaid. 

 By John W. Harshberger, V'a.S)., Profes- 

 sor of Botany, University of Pennsylvania; 

 Member Botanical Society of America; Vice- 

 President Ecological Society of America, etc. 



PLANCK. The Theory of Heat Radiation. 



With an Appendix, List of Original Papers. 

 Illustrated. Svo. Cloth, $2.25 Postpaid. 

 By Max Planck, Professor of Mathe- 

 matics and Physics and Di7-ect. hist. Theoret. 

 Phys., Berlin University. Translated from 

 the Second German Edition by Morton 

 Masius, Ph.D., Department of Physics, 

 Worcester Polytechnic Institute, Mass. 



Publishers 



PHILADELPHIA 



< < 



HALOFIDE CELL" 



A NEW LIGHT REACTIVE RESISTANCE 

 OF GREAT SENSITIVITY 



These'new cells will lower their electrical resistance 100 per cent. 



on exposure to .25 of a foot candle when the source used is a 



Tungsten Filament. Special cells are constructed which will do 



this in .06 of a foot candle. 



Their recovery after exposure is extremely rapid as also is 

 their response to the light stimulus which 

 is in marked contrast to the Selenium Cell, 

 especially on exposure to very low light 

 intensities. 



Write for Particulars 



Case Research Laboratory 



AUBURN, NEW YORK 



