STUDIES IN PLANT RESPIRATION AND PHOTOSYNTHESIS. 1 1 



to serve as a modulator to the mechanists and bring the realization 

 that pronouncements on the mechanistic view of life processes can be 

 made only with reserve and as partial truths. 



The term ''living matter" is in a sense anthropomorphic, in that 

 we ascribe to the matter of living things attributes and qualities 

 which we recognize in our own behavior. This is in a large measure 

 responsible for the confusion in our conception of the essential nature 

 of the processes in living things, we having superimposed on the 

 matter of vegetable organisms the behavior of our own tremendously- 

 complex system, including the maze of mental and spiritual expe- 

 riences. The differences in the two conceptions at first seem insig- 

 nificant or subtle, the one of ''living matter," the other of "life in 

 matter"; but from the experimental physical-chemical viewpoint 

 the differences are fundamental. 



The gap between li\dng and non-living substances in a cell has 

 never been bridged nor have the differences ever been clearly defined. 

 To the proteins has been ascribed the function of life, partly because 

 of their complex structure and reactions and also because they have 

 been found wherever vital phenomena occur. That the proteins 

 form an essential part of the medium in which these complex chemical 

 reactions, called "life," take place, and that the proteins or their 

 derivatives contribute directly or through catalytic action to these 

 reactions, embodies a conception which is compatible with our modern 

 physical-chemical thinking. This conception of a relatively inert 

 substance or medium in which the interplay of chemical reactions 

 takes place, and through which these always manifest themselves 

 as life activities, is advanced, of course, not as describing the actual 

 state of affairs, but as a hypothesis which lends itself to experimental 

 investigation. Thus in the plant-cell the carbohydrates and fats 

 serve as the fundamental sources of energy in respiration. The 

 nitrogen derivatives, with which the plant deals most economically 

 as proteinaceous compounds, constitute an essential portion of the 

 medium in which the multiplicity of reactions occur. Furthermore, 

 these proteins, of themselves inert, are of fundamental importance 

 because of their ability, through their decomposition products — 

 the amino-acids — to influence the enzymatic reactions. The dif- 

 ferences in protoplasm are thus to be ascribed to the differences in 

 the media in which the various reaction complexes occur. Pro- 

 toplasm is to be regarded as a colloidal mass of varying composition, 

 which serves as a medium for the manifold chemical reactions 

 involving the breakdown of many molecules, thus releasing energy 

 which may be used for the synthesis of new compounds, which in 

 turn may be incorporated in the colloidal mass of the substratum. 

 Nor can such a hypothesis explain or define life. It simply attempts 



