IV. 



THE FACTORS OF ORGANIC EVOLUTION FROM 

 THE STANDPOINT OF EMBRYOLOGY. 



By Prof. Edwin Grant Conklin, 



Our knowledge of the mechanics of evolution must 

 always depend in large part upon the study of indi- 

 vidual development. More than any 

 Embryology ^^^^^ science, embryology holds the 



, r , ,• keys to the method of evolution. If on- 



od of evolution. -' -^ 



togeny (life history of the individual) is 

 not a true recapitulation it is at least a true type of evo- 

 lution, and the study of the causes of development will 

 go far to determine the factors of phylogeny or race 

 development. 



The causes and methods of evolution are intimately 

 bound up with those general phenomena of life, such as 

 assimilation, growth, differentiation, metabolism, inher- 

 itance, and variation ; and the evolution problem can 

 never be solved except through a study of these general 

 phenomena of life itself. Our great need at present is 

 not to know more of the course of evolution, but to dis- 

 cover, if possible, the causes of growth, differentiation, 

 repetition, and variation. All these general phenomena 

 are most beautifully illustrated in the development of 

 individual organisms, and because they are fundamental 

 to any theory of evolution I shall dwell upon them 

 xoo 



