ORIGIN OF SPECIES 243 



The pattern having become rigid, succeeding genera- 

 tions demonstrate the "fixity of species." 



At several great periods in the earth's history, 

 according to my theory, countless separate life-forms 

 could originate, doubtless did originate at the same 

 time. In each case, the process of development 

 (evolution) inevitably continued until the form be- 

 came rigid. Eventually, then, each of these different 

 forms necessarily resulted in one or more separate 

 species. 



That these conclusions have direct bearing on the 

 problem of man's descent is obvious. The doctrine 

 of man's descent is no stronger than the weakest link 

 in the general descent theory. But that absolute 

 specificity rules in all life-processes as in all other 

 processes, cannot longer be doubted by anyone who 

 is familiar with atomic physics. 



Therefore, emphatically, the painful crudity, the 

 vague generalizations, and the inexactness of the old 

 forms of expression relative to the facts of the di- 

 versity of life-forms and their causes, which have 

 been current in most of the evolutionary literature 

 of the fifty and more years after Darwin, must be 

 rejected utterly. High-sounding generalizations, 

 however plausible, are absolutely meaningless to a 

 physicist or a physical chemist. He knows only exact 

 quantities and quantitative relations and their re- 



