THE EVOLUTION OF LIFE 



ism, by trying to cxpLiin the complex process of in- 

 dividual develo])mcnt, for the whole frame and every 

 single part of it, by causal connection with the stem- 

 history of our animal ancestors. In the latest edition of 

 this monistic "ontogeny of man" I gave numbers of il- 

 lustrations (thirty plates and five hundred engravings) of 

 these intricate structures, and endeavored to make the 

 subject still plainer by the addition of sixty genetic 

 tables. I may refer the reader to this work,' and not 

 dwell any further here on the biogenetic law, especially 

 as one of my pui)ils, lleinrich Schmidt (of Jena), has 

 recently described its biological significance and its 

 earlier history and ])resent position in a very clear and 

 reliable little work {HaeckeVs Biogenetic Law and its 

 Critics). I will only add a word or two on the struggle 

 that has taken place for thirty years over the complete 

 or partial recognition of the biogenetic law, its em- 

 pirical establishment, and its philosophic application. 



In the very name, "fundamental law of biogeny," 

 which I have given to my recapitulation theory, I claim 

 that it is universal. Every organism, from the uni-l 

 cellular protists to the crytogams and ccrlenteria, and 

 from these up to the flowering plants and vertebrates, 

 reproduces in its individual development, in virtue of 

 certain hereditary processes, a part of its ancestral his- 

 tory. The very word "recapitulation" imj)lics a partial ^ 

 and abbreviated repetition of the course of the original 

 phyletic development, determined by the "laws of 

 heredity and adaptation." Heredity brings about the 

 reproduction of certain evolutionary features; adapta- 

 tion causes a modification of them by the conditions of 

 the environment — a condensation, disturbance, or falsi- 

 fication. Hence I insisted from the first that the bio- 

 genetic law consists of two parts, one positive and palin- 



* As already stated, it will presently appear in England with 

 the title. The Evolution of Man. — Trans. 



3S1 



