PLANT PHYSIOLOGY AS A SCIENCE 5 



Observation has suggested, for example, that light is necessary for the con- 

 tinued existence of plants. To one who is scientifically minded, either by 

 instinct or training, the obvious next step is to test this postulate experimen- 

 tally. If the suggested hypothesis is substantiated by experiment it is ten- 

 tatively accepted as a theory. Theories such as those proposed in explanation 

 of the processes or reactions of plants, together with the experimental results 

 which are considered to support them, are usually published in a scientific 

 journal or monograph and thus exposed to evaluation and further experimen- 

 tal testing by other scientists. 



Continued experimentation may lead to substantiation, rejection, or modifi- 

 cation of the theory as originally proposed. Modification would undoubtedly 

 be the fate of the hypothesis used as an example, since sooner or later some 

 investigator would find that non-green plants can thrive in the absence of light. 



Experiments often raise more questions than they answer. New approaches 

 to the problem under consideration as well as desirable new lines of inquiry 

 are constantly opening up to the alert investigator. In this way experimenta- 

 tion leads to more experimentation, more facts accumulate, and more theories 

 are proposed. Some of the suggested hypotheses are confirmed, others are 

 rejected, and still others are modified. Most of them, sound or fallacious, in 

 turn suggest further observation and experimentation. As a result of such 

 endless and painstaking labors there is slowly built up that vast, complex, and 

 ever-changing body of knowledge which we refer to as a science. 



The system of subjecting all hypothetical explanations of natural phenom- 

 ena to experimentation is the essence of the scientific method. It is the char- 

 acteristic methodology of all sciences. Progressive modification of accepted 

 concepts in the light of new experimental findings continually increases the 

 soundness of scientific generalizations. Thus there are incorporated into any 

 science theories and generalizations in various stages of acceptance. Some 

 stand upon such a firm substructure of facts that they are accepted by all 

 authorities in the field. Others, less securely supported by experimental results, 

 are subscribed to by some but rejected by other workers. Finally, in any 

 science there are alwa5's some theories which are so dubious that they find only 

 a few advocates. Furthermore, some of the theories now widely held sooner 

 or later will be discarded as a result of new findings or as a consequence of 

 different interpretations of facts already known. 



However, not all scientists are in agreement regarding the interpretation 

 of the same sets of facts. Although this state of affairs is entirely consistent 

 with the spirit of scientific research, it is frequently puzzling to students and 

 laymen. Differences of opinion regarding the hypotheses which suitably ex- 

 plain scientific phenomena are most likely to arise when experimental data are 



