10 The Recapitulation Theory and Human Infancy 



recapitulation an integral element in this theory and gave it its- 

 new form. Early in his life Agassiz entered upon elaborate 

 studies of living and fossil fishes and so came upon resemblances 

 between developmental phases of living animals and the adult 

 forms of their extinct representatives. As his interest broadened 

 to include the systematic classification of the whole animal 

 world, Agassiz relied more and more upon the facts of embry- 

 ology to make good the deficiencies of fossil remains and to pre- 

 vent the confusion, inevitable as he believed, from an examina- 

 tion of anatomical differences alone. In 1857 he wrote, "I satis- 

 fied myself long ago that embryology furnishes the most trust- 

 worthy standard to determine the relative rank among animals. " 

 In the system ultimately evolved by Agassiz, descriptive of 

 what he believed to be the natural order, there were four great 

 parallelisms, or systems of relationship. These were (1) a paral- 

 lelism between the geological succession of animals and their 

 relative standing or structural gradation; (2) a parallelism be- 

 tween the geological succession of animals and the individual 

 development of their living representatives; (3) a parallelism 

 between the relative rank or gradation of animals and their 

 individual development; and (4) these several series were again 

 related to geographical distribution. Thus 



"the phenomena of animal life correspond to one another, 

 whether we compare their rank as determined by structural 

 complication with the phases of their growth, or with their suc- 

 cession in past geological ages; whether we compare this succes- 

 sion with their embryonic growth, or all these different relations 

 with each other and with the geographical distribution of ani- 

 mals upon earth. The same series everywhere!' 712 



This interlocking system of relationship constituted the ground- 

 work of the "plan of creation" Agassiz's "Essay on Classifica- 

 tion" was meant to delineate, a plan very satisfying to his own 

 religious sentiments, if indeed it was not inspired by them. 

 "Shall we," he exclaims, "by any false argumentation, allow 

 ourselves to deny the intervention of a Supreme Intellect in 

 calling into existence combinations in nature by the side of 

 which all human conceptions are child's play?" 13 



"Essay on Classification, 1857, p. 196. 

 "Ibid., p. 197. 



