DARWIN AND PALEONTOLOGY 217 



organs, of the best fitted variations in these, and 

 finally come down to the focal point that the 

 causes of adaptation and the origin of species 

 ultimately center around constant variability and 

 the survival or selection of minute variations. 

 From his exhaustive knowledge of Darwin's 

 work Professor Poulton holds that the great phi- 

 losopher had in mind as the material for Natural 

 Selection small variations^ congenital and inher- 

 itable; he knew well that the material included 

 "great and sudden variations" hut he did not 

 believe that they were selected. His variations 

 had no power of developing in definite direction. 

 Direction was given by Selection. That is, it 

 remained for selection to give direction by choos- 

 ing from all variations those which happened to 

 be in an adaptive direction. 



It is obvious that as we pass from the broad 

 to the minute the theoretic demand upon the 

 selection hypothesis becomes more and more in- 

 tense, but the tendency of our time is to waive 

 aside theoretic considerations and come down to 

 actual observations and facts and see how far 

 they support the Darwinian and other hypoth- 

 eses, and how far they call for new hypotheses 

 and interpretations. 



Thus the question of the hour is to see what 

 parts of this entire hypothetical system of selec- 

 tion within selection, until we reach the minute, 

 are in accord with modern paleontological evi- 

 dence. 



