376 PROGRESS OF SCIENCE IN THE CENTURY. 



Meckel in 1821 wa8 one of the first to speak of the 

 "correspondence between the development of the 

 embryo and that of the entire animal series." Kiel- 

 meyer seems to have something to do with the origi- 

 nation of the idea ; Oken and Goethe both express it. 

 Yon Baer, to whom the recapitulation-idea is often 

 carelessly ascribed, was very cautious on the subject; 

 Louis Agassiz (though a non-evolutionist) gave it 

 clear expression in his famous Essay on Classifica- 

 tion (1859) ; his son Alexander was also an adher- 

 ent, though more guardedly; Fritz Miiller was an 

 enthusiastic exponent in his Facts for Darwin, 

 Haeckel formulated it in his " Biogenetisches Grund- 

 gesetz " (fundamental biogenetic law) that " Ontog- 

 eny tends to recapitulate Phylogeny " ; and Her- 

 bert Spencer also made it part of his biological 

 system.* 



There is no doubt that we have here a big idea 

 and a clear one, that of individual development in 

 some measure recapitulating racial history, and it 

 must not be hastily condemned because of popular 

 exaggerations on the one hand (no idea has suffered 

 more from its friends), or because critics have sought 

 rather to controvert than to correct it. Let us admit 

 the grotesqueness of popular exposition, e.g., that 

 the mammal is at one time a little fish ; let us allow 

 that Milnes Marshall did not mean to be taken too 

 literally when he spoke of " every animal climbing 

 up its own genealogical tree " ; let us grant that evi- 

 dence from the child's acquirement of language and 

 ideas is not very cogent evidence of parallelism to 

 a past whicK is more than half-concealed; let us 

 remember Haeckel's explicit declaration that the 



* For some details, see the writer's Science of Life, pp. 133- 

 138. 



