6l6 WENT 



what it is today, to trace causal relationships between our sister sciences and 

 ourselves, to enquire into the role government, private enterprise, social condi- 

 tions, organization, education, publication policies, and professional organiza- 

 tions have played in our development. 



The experimental method, which lies at the basis of plant physiology, had 

 its real inception in the 17th century, but it started to come into its own in 

 biology about a century ago. The world in general owes America a debt of 

 gratitude when it led in the 1870s with the introduction of the experimental 

 method into agriculture with the establishment of government-supported Ag- 

 ricultural Experiment Stations. Except as far as plant nutrition was con- 

 cerned, plant physiology did not have its own place in these experiment sta- 

 tions, but it became an important subject in connection with investigations in 

 plant pathology, horticulture, agriculture, and recently in forestry, so that at 

 present more than half of all plant physiological work is carried out in experi- 

 ment stations and college and university departments of applied botany. This 

 clearly points out that with the present structure of society, large-scale finan- 

 cial support of research is possible only when such research has a demonstrable 

 practical implication. 



Admitting that the experimental method now is thoroughly entrenched in 

 most branches of science, and was so in plant physiology long before it started 

 to blossom in the United States, we now should see to what extent other 

 sciences have contributed to the advances in plant physiology, especially in 

 the last half century. The invention of printing and the development of the 

 microscope, those two most important factors in the growth of botany as a 

 science, sufficiently antedated the inception of plant physiology as not to be 

 factors in its development. We might almost say that the opposite is true. 

 For not enough plant physiology is carried out on the cellular level. 



After Stephen Hales' famous Vegetable Staticks almost any advance in 

 chemistry was soon followed by a comparable advance in botany. The dis- 

 covery of photosynthesis was almost simultaneous with the discovery of 

 oxygen; elementary analysis led de Saussure to his biochemical analysis of 

 respiration; and the chemical isolation of hormones and vitamins gave rise 

 to their application in the control of plant development. In some cases 

 physiology even spearheaded advances in other sciences, such as Dutrochet's 

 work on osmosis. Pfeffer's quantitative measurement of osmotic pressure 

 formed the basis for van't Hoff's theory of this phenomenon, while de Vries' 

 isotonic coefficients provided strong evidence for the dissociation theory of 

 electrolytes. Biochemistry had its inception as a joint effort by physiologists, 

 microbiologists, and chemists, to which all contributed simultaneously and 

 equally. 



The direct impact of mathematics on plant physiology has not been very 

 great. There is a natural tendency among biologists to express their facts and 

 fancies in as precise terms as possible, which naturally leads to the symbolism 



