PALINGENESIS AND KENOGEXESIS. II 



of the greatest importance to scientific Phylogeny, which, 

 from the available empiric material supplied by Ontogeny, 

 by Comparative Anatomy, and by Palaeontology, seeks to 

 infer the long extinct historical processes of tribal evolution. 

 It is of the same importance to the student of evolution 

 as is the critical distinction between corrupt and genuine 

 passages in the text of an old writer to the philologist ; the 

 separation of the original text from interpolations and corrupt 

 readings. This distinction between Palingenesis or inherited 

 evolution, and Kenogenesis or vitiated evolution, has not, 

 however, yet been sufficiently appreciated by naturalists. 

 But I believe that it is the first condition requisite, if the 

 history of evolution is to be really understood, and I think 

 that two separate main divisions, based on this distinction, 

 must be made in germ-history; Palingenesis or inherited 

 history, and Kenogenesis or vitiated history. 



Let us illustrate this highly important distinction by a 

 few examples taken from the evolution of man. In Man, as in 

 all other higher Vertebrates, the following incidents of germ- 

 history must be regarded as palingenetic processes : the 

 formation of the two primary germ-layers, the appearance 

 of a simple notochord (Chorda) between the spinal tube and 

 the intestinal tube, the transitory formation of gill-arches 

 and gill-openings, of primitive kidneys, of the primitive brain 

 bladder, the hermaphrodite rudiment of the sexual organSj 

 etc All these, and many other important phenomena have 

 evidently been accurately handed down, by constant heredity, 

 from the primaaval ancestors of Mammals, and must, there- 

 fore, be referred directly to corresponding palseontological 

 evolutionary incidents in the history of the tribe. On the 

 other hand, this is not the case with the following germinal 



