THE 



RADIO-ATMOMETER 



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

 widely known. The manner in which it may be used 

 in conjunction with the white Atmometer in studies of 

 light intensity has been described by the devisor, Prof. 

 B. E. Livingston, in the following papers: 



The Plant World, 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 



A Choice Collection of Morphological Material 



Is offered for sale, including a full representation of all groups of cryptogamic 

 plants. A portion of the collection is preserved in alcohol, the remainder is 

 imbedded in parafBne ready for sectioning. 



A complete list with prices will be sent on application. 



THE PLANT WORLD, TUCSON, ARIZONA 



