252 ERNST HAECKEL AND CARL GEGENBAUR 



he made of it, Haeckel went a step beyond Darwin, and 

 exercised perhaps a more direct influence upon evolutionary 

 morphology than Darwin himself. 



Haeckel was not the original discoverer of the law of 

 recapitulation. It happened that a few years before the 

 publication of Haeckel's General Morphology, a German 

 doctor, Fritz Miiller by name, stationed in Brazil, had been 

 working on the development of Crustacea under the direct 

 inspiration of Darwin's theory, and had published in 1864 

 a book 1 in which he showed that individual development 



clue to ancestral history. 



conceived that progressive evolution might take place 

 in two different ways. "Descendants . . . reach a new goal, 

 either by deviating sooner or later whilst still on the way 

 towards the form of their parents, or by passing along this 

 course without deviation, but then instead of standing still 

 advancing still farther" (Eng. trans., p. ill). In the former 

 case the developmental history of descendants agrees with 

 that of the ancestors only up to a certain point and then 

 diverges. " In the second case the entire development of 

 the progenitors is also passed through by the descendants, 

 and, therefore, so far as the production of a species depends 

 upon this second mode of progress, the historical develop- 

 ment of the species will be mirrored in its developmental 

 i_history " (p. 112). 



"TOf course the recapitulation of ancestral history will be 

 neither literal nor extended. " The historical record preserved 

 in developmental history is gradually effaced as the develop- 

 ment strikes into a constantly straighter course from the 

 egg to the perfect animal, and it is frequently sopJiisticatcd 

 by the struggle for existence which the free-living larv.x- 

 have to undergo" (p. 114). 



It follows that "the primitive history of a species will be 

 preserved in its developmental history the more perfectly 

 the longer the series of young stages through which it passes 

 by uniform steps ; and the more truly, the less the mode of 

 life of the young departs from that of the adults, and the less 

 the peculiarities of the individual young states can be c<>n- 



1 h'iir Darwin, 1864. KM;.;, trans, by D.illas &S, Facts and Arguments 

 for Darwin^ London, i86y. 



