AGRICULTURAL INDUSTRIES 175 



fide in killing armored scales on dormant deciduous 

 trees, which is now universally employed for that 

 purpose; discovered the availability of hydrocyanic 

 gas for insect killing on tented evergreen trees and 

 saved her citrus industry by systematic and timely 

 invention which rendered the use of this treatment 

 practicable and profitable ; first made great and strik- 

 ing demonstration of success in bringing from abroad 

 the natural enemy of an injurious insect which ar- 

 rested the latter's progress and made world search for 

 beneficial insects and introduction of them a sus- 

 tained State policy. In a very different phase of 

 fruit protection, California was first to demonstrate 

 the feasibility of 'frost prevention by direct heating 

 of the atmosphere. 



Fourth, the relation of new varieties to commer- 

 cial fruit production. New varieties of fruits have 

 been originated, which, in the case of peaches, plums, 

 almonds and walnuts, constitute the larger part of 

 the commercial product; the immense citrus fruit 

 production has been built up with varieties of espe- 

 cial suitability which were not commercially im- 

 portant elsewhere. All these fruits of California birth 

 and adoption have now a place in the world pomolo- 

 gies and are becoming important abroad in all re- 

 gions which have natural conditions resembling our 

 own. In addition to his notable contributions to this 

 attainment, the unique conceptions and original meth- 

 ods of Luther Burbank have given California popular 

 repute for leadership in plant-breeding and have 

 stimulated public interest in plant improvement. 



