58 The Recapitulation Theory and Human Infancy 



ment displayed in succession the forms of animals as they 

 ranged in a single series one above the other. In one instance 

 this was regarded as a rehearsal of the story of creation of these 

 forms (Oken). Von Baer's suggestion that the prevailing idea 

 was an error and that the resemblances were between embryos 

 of the four great types, to be detected among animals, was for 

 the time disregarded, in favor of a conception of Agassiz of a 

 parallelism between the succession of geological forms as in- 

 dicated by fossils and the succession of stages in development, 

 a parallelism expressive of one feature of the divine plan of cre- 

 ation. ^With the advent of the theory of descent with modi- 

 fication the facts of the older view were invoked in support of 

 the theory, and Darwin, with the help of Fritz Muller, showed 

 how a genetic classification could be determined in large part 

 with the aid of embryology. Darwin's moderate acceptance 

 of the theory of a developmental rehearsal or recapitulation of 

 racial history, was supplanted by the radical statements of 

 Haeckel, who, by misconceiving the effects of heredity and 

 adaptation through successive generations, formulated a " bio- 

 genetic fundamental law," which implied that by necessity on- 

 togenies must preserve an abbreviated and condensed record 

 of phylogeny. Herbert Spencer helped to extend the influ- 

 ence of this view by accepting it in general, while showing in 

 some detail its limitations. Recapitulation derived new war- 

 rant from a series of important investigations made by Hyatt 

 and his followers upon fossil shells of some invertebrates, which 

 showed how by the acceleration and retardation of adult char- 

 acters in ontogeny a record of the phylogeny was preserved. 

 The palaeontologists of this school to-day constitute the chief 

 advocates of the views of recapitulation as supplying a fairly 

 faithful record of phylogeny in many cases. Among the embry- 

 ologists the ancestral record in ontogeny was acknowledged 

 and employed for a considerable period until absurdities due 

 to its extreme application greatly impaired its prestige. At 

 the present time the weight of authority favors an explanation 

 of established ancestral traces in ontogeny as being due to 

 the transmission of similar embryonic and larval conditions 

 through successive descendants, while admitting the retention 

 of adult characters in ontogeny in some instances. These traces 

 are not such, however, as to present in any real sense a chrono- 



