FIFTY YEARS OF PLANT PHYSIOLOGY IN THE U.S.A.

PLANT PHYSIOLOGY as a separate branch of botany is just 100 years old; its beginning can be traced back to the start of the career of Julius Sachs. Here in the United States it can properly be said that plant physiology is just about 50 years old, and many of the botanists who started their careers in the early nineteen hundreds by studying the life processes of the plant are still with us today. A really authentic history could have been presented if Allard, Duggar, Kraus, McDougal, Osterhout, Shantz, Shive or Shull had been asked to do so, but these men have earned their emeritate and should not be called upon to perform still further tasks which we younger men can do by looking up the records of their performances. I hope, however, that they will be willing to provide footnotes, and add to what I can only inadequately present in half an hour. For most of you of the old guard the trip to Storrs may have become too strenuous. We, who have seen you so often at our yearly meetings, and the younger ones who have not had that privilege, we all salute you and we rededicate ourselves to furthering botany in the next 50 years, as you did in the previous half century. History can be approached in many different ways. But since we are dealing with such recent history, it seems better not to stress personalities who actually made this history. A proper evaluation of the contributions of each plant physiologist in the U. S. during the last 50 years is utterly impossible at present. In so many cases the stimulation coming from research, teaching, critical evaluation or organization in the past 50 years cannot be judged until the next fifty years have elapsed. Towards the end of this talk I will try to give you shortly my own personal evaluation of specific events and investigations, but to begin with I would like to apply the physiological method to the history of plant physiology. Or, to put it more accurately, I would like to analyze the forces which seem to have molded our science into what it is today, to trace causal relationships between our sister sciences and ourselves, to enquire into the role government, private enterprise, social conditions, organization, education, publication policies and professional organizations 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 wvhen it led in the 1870's with the introduction of the experimental method into agriculture with the establishment of government-supported Agricultural Experiment Stations. Except as far as plant nutrition was concerned, plant phvsiologv did not have its own Dlace in these experiment stations, 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 experiment stations and College and University departments of applied botany. This clearly points out that with the present structure of society, large-scale financial 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 U.S., 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 a factor 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 discovery 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 of mathematical formulae, but their further development did not require more than the standard methods of calculus. It is possible that the new electronic computers will in the future contribute significantly to the development of biology, where the highly complex interrelationships between constituent parts, whole organisms and environment require equally complex mathematical treatment. It would not be correct to mention the increased