2io PRIMARY FACTORS OF ORGANIC EVOLUTION. 



or caenogeny. If we could study the embryology of 

 the many extinct forms of life, the missing stages 

 would all be found, but as we have not the opportun- 

 ity of pursuing this important research, we have to 

 rely on paleontology for our phylogeny. Paleontology 

 is and always will be imperfect, but all that we get is 

 palingeny, or the phylogeny itself, and not an inverted 

 and distorted record of it. 



