xxii INTRODUCTION 



originally discovered and elaborated by physiologists and is now 

 widely used, not only for ornamental plants, but also in potato 

 culture, as are also the methods of application of electric light 

 and other forms of radiant energy in plant culture. With further 

 progress in physiology and its increasing unity and coordination 

 with the practice of agriculture and with the gradual adoption 

 of the methods of scientific agriculture, we have the right to 

 expect from physiologists the creation of further new and valuable 

 cultural methods, which may raise agriculture to an unforeseen 

 prosperity. 



