THE 



RADIO-ATMOMETER 



Is a black-brown form of the white Atmometer, already 

 widely known. The manner in which it may be used 

 in conjunction with the white Atmometer in studies of 

 light intensity has been described b}' the devisor, Prof. 

 B. E. Livingston, in the following papers: 



The Plant Worlds vol. 14, pp. 96-99, May, 191 1. 



The Botanical Gazette, vol. 52, pp. 418-438, December, 1911. 



These black-brown cups can now be supplied in the natural 

 state at $1.00 each; $8.00 per 10. 



THE PLANT WORLD 



TUCSON ARIZONA 



THE F. RONSTADT CO. 



TUCSON - - ARIZONA 



AGENTS FOR 



PLANET JR. GARDEN TOOLS, IMPLEMENTS, PUMPS 

 ENGINES AND WINDMILLS 



CACTUS CANDY 



Delicious, fresh from the farm. 

 Per pound 50c. by parcel post. 



WRIGHTSTON FARMS 



WRIGHTSTOWN, ARIZONA 



