VARIOUS THEORIES OF THE ORGANISM 17 



The solution of the problem of differentiation has scarcely been 

 attempted. It is manifestly closely associated with the metabolic 

 process, but what is the origin and significance of the different 

 kinds of proteid substance and how is their localization at different 

 points of the organism accomplished? If the " labile ' : biogene 

 molecules all possess the same constitution, then they must undergo 

 different transformations in different parts of the organism; if 

 they differ in constitution in different parts we must find some 

 basis for the difference. It is an established fact that the basis of 

 differentiation exists within the organism and not in environmental 

 factors: it must then depend in some way upon the labile proteid 

 molecule which according to the hypothesis is the basis of life. 

 But it is difficult to understand how such molecules can serve as a 

 foundation for localization and differentiation. 



If we accept this hypothesis we must after all conclude that the 

 processes in the living organism differ very widely from those in 

 the inorganic world, for nowhere except where there is life do we 

 find anything approaching in any degree the synthesis of so com- 

 plex and highly labile a substance as the living substance is assumed 

 to be. But even if we should ever succeed in producing in the 

 laboratory a proteid with the degree of lability postulated for the 

 living substance, it would be likely, in the absence of the delicate 

 mechanism regulating its transformation in the organism, to die 

 or " explode" at once. 



From this point of view it is also difficult to account for the 

 capacity of organisms to continue alive when subjected to the 

 never-ceasing changes in the world about them. We should 

 scarcely expect such extremely delicate and sensitive mechanisms 

 as these highly labile molecules to withstand the shocks to which 

 organisms in nature are constantly subjected. The facts indicate 

 that organisms have existed continuously for millions of years and 

 during this time have given rise to inconceivable amounts of 

 "living substance." How could such a labile substance ever have 

 persisted long enough in the first instance to form an organism ? 



The only way in which we can account for these facts without 

 discarding the hypothesis of a highly labile living substance is by 

 the assumption that in some way a part of the energy liberated by 

 the breakdown of these labile molecules must serve for the synthesis 



