THE EVOLUTION OF LIFE 



stand their significance. The principle also makes clear the 

 wide gulf that separates the older teleological and dualistic 

 morphology from the modem mechanical and monistic science. 

 If the physiological functions of heredity and adaptation are 

 proved to be the sole causes of organic construction, every kind 

 of teleology, and of dualistic and metaphysical explanation, is 

 excluded from the province of biogeny. The irreconcilable 

 opposition between the leading principles of the two is clear. 

 Either there is or is not a direct and causal connection between 

 ontogeny and phylogeny. Either ontogenesis is a brief com- 

 pendium of phylogenesis or it is not. Either epigenesis and 

 descent — or pre-formation and creation. 



In repeating these principles here, I would lay stress 

 particularly on the fact that, in my opinion, our "me- 

 chanical biogeny" is one of the strongest supports of 

 the monistic philosophy. 



