VARIOUS THEORIES OF THE ORGANISM 13 



governed by different laws still plays no small part in interpretation 

 and speculation, and we have heard much of unit characters within 

 the last few years. The chromosomes and their hypothetical 

 constituent elements still serve their purpose as safe repositories 

 of unsolved problems, and doubtless will long continue to do so. 

 And in Rignano's theory of centro-epigenesis ('06) we have a cor- 

 puscular theory in a new dress, but still with the same characteristic 

 features. 



But all of these theories and conceptions bear the stamp of the 

 study rather than of the laboratory. Many of them show great 

 ingenuity, but they all fail to show us how the things are done that 

 they assume to be done: they ignore almost entirely the dynamic 

 side of life. At present we can neither prove nor disprove them, 

 for they are entirely beyond the reach of science. No facts can 

 overthrow them, for it is always possible to make the hypothetical 

 units behave as the facts demand. But we can at least look in 

 other directions for a more satisfactory basis for interpretation of 

 the facts of observation and experiment and for guidance in our 

 thinking. 



CHEMICAL THEORY 



The synthesis in the laboratory of organic substances which 

 began in 1828 with the synthesis of urea by Wohler led to the 

 overthrow of the doctrine of vital force current before that time. 

 The formulation of the law of conservation of energy by Robert 

 Mayer, its establishment by Helmholtz, and its application to 

 organisms by both of these investigators as well as by others, con- 

 tributed still further to the belief that the dynamic processes in 

 organisms, instead of being unique and governed by special laws, 

 are not fundamentally different from those which occur inde- 

 pendently of life. And, finally, the acceptance of the theory of 

 evolution gave a breadth of outlook never before attained, in that 

 it permitted us not only to regard the organic world as one great 

 whole, but also afforded a firm foundation for the belief that the 

 living must have arisen from the lifeless and that the fundamental 

 laws governing both are the same. 



With the attainment of this point of view the problem of the 

 nature of the processes in the living organism was fully established 



