10 THE EVOLUTION OF MAN. 



prove the deep harmony, and original parallelism, be- 

 tween the two series. By adducing numerous facts, I hope 

 to convince my readers that from the actually existing 

 series of embryonic forms which can be shown at any time, 

 we are able to draw the most important conclusions as to 

 the genealogical tree of the human species. We shall thus 

 be able to form a general picture of the series of animal 

 forms which succeeded each other as the direct ancestors of 

 man, in the long course of the history of the organic world. 



In this phylogenetic significance of ontogenetic phe- 

 nomena, it is of course most important to distinguish clearly 

 and exactly between the original, palingenetic processes of 

 evolution, and the later kenogenetic processes of the same. 

 The term Palingenetic process^ (or reproduction of the history 

 of the germ) is applied to all such phenomena in the history 

 of evolution as are exactly reproduced, in consequence of 

 conservative heredity, in each succeeding generation, and 

 which, therefore, enables us directly to infer the corre- 

 sponding processes in the tribal history of the developed 

 ancestors. The term Kenogenetic process^ (or vitiation of 

 the history of the germ) is applied to all such processes in 

 the germ-history as are not to be explained by heredity 

 from primseval parent-forms, but which have been acquired 

 at a later time in consequence of the adaptation of the 

 germ, or embryo form, to special conditions of evolution. 

 These kenogenetic processes are recent additions, which do 

 not allow of direct inference as to the corresponding pro- 

 cesses in the tribal history of the ancestral line, but which 

 rather falsify and conceal the latter. 



This critical distinction between the primary palinge- 

 netic, and the secondary kenogenetic processes is of course 



