2 BURTON EDWARD LIVINGSTON 



these are terms now frequently heard among those who are not 

 scientists, and often encountered in the daily press. Unknow- 

 ingly, perhaps, the world is coming to look more and more to 

 the scientists, for its utilities, for its amusements, and even 

 for its philosophy and practical religion. Although physiology 

 has been one of the last of the sciences to enter upon this phase 

 of popularization, its progress in this direction has, nevertheless, 

 been very rapid, especially since the closing years of the last 

 century. On the animal side mainly through the arts of medi- 

 cine and surgery, on the plant side mainly through those of 

 agriculture and forestry, many of its elementary principles 

 have become incorporated into general knowledge. The popular- 

 ization of a knowledge of the mineral needs of plants, for example, 

 has largely occurred in the period that we are considering. 



This phase of plant physiological development, based largely 

 on utihtarian desires, has made possible the establishment and 

 rapid growth of many great institutions, such as the United 

 States Department of Agriculture and numerous experiment 

 stations throughout the world, and these, in turn, have furnished 

 opportunity for the carrying out of an ever-increasing number 

 of truly scientific researches on the dynamics of plant processes. 

 There seems to be no limit to this kind of growth, and it is safe 

 to predict that the next quarter-century will produce a still 

 more general and clearer appreciation of both the utilitarian and 

 the philosophical value of a knowledge of what plants do and 

 how and why they do it. Anything that may advance this 

 general appreciation should also hasten the development of the 

 science itself. 



Turning to the internal growth of physiology, I wish to mention 

 first some alterations in general physiological philosophy that 

 have become especially evident during these twenty-five years, 

 and afterw^ards to direct your attention to a few of what appear 

 to me as important forward steps in the special science of plant 

 physiology. 



Development of deterministic philosophy. Perhaps the most 

 striking growth, or alteration, in physiological philosophy, to 

 be detected by a comparison of the writings of the '70's and 



