The Recapitulation Theory in Biology 43 



development, and the present embryos must pass also through 

 lower stages in order to reach the higher. But it is by no means 

 necessary for the later, higher forms to pass through embryonal 

 forms because their ancestors have once existed in this condition" 68 



Haeckel's phylogenetic method is therefore "a mere by-path," 

 and is "not necessary at all for the explanation of the facts of 

 embryology." 



The implications of the germinal origin of variations were indi- 

 cated by Hatschek in these sentences: 



"When one premises (as Haeckel does) that the modifications 

 which the developed individual inherits directly through outer 

 influences become hereditary in its descendants, then the ex- 

 planation shapes itself very simply. The new acquisitions of 

 the adults bring about immediately a prolongation, in the single 

 generation very insignificant, in the course of generations in- 

 creasing, of the ontogenetic row of forms in the descendants. 

 But when one holds fast to the view that only those newly oc- 

 curring characters become inherited, which have arisen through 

 variation of the reproductive cells .... another explanation seems 

 necessary. One must presuppose 'overstepping varieties.' With 

 this name I would call such varieties as consist in a prolongation 

 of the ontogenetic row of forms." 69 



From this conception another seems to follow: 



"We must consider it as a general law, derivable from the 

 principle of causality, that with the phylogenetic modification 

 of the animal form (individual cycle) never only the end stage 

 becomes changed, but always the whole row from egg cell to 

 the end stage. Each modification of the end stage necessitates 

 a change of the egg cell itself." 70 



In view of the truth contained in the last sentence, we must 

 believe that through the course of descent from the unicellular 

 condition to the existing higher species, the germ cell has under- 

 gone an evolution from simple to complicated conditions, cor- 

 responding to the difference in organic complication suggested 

 by a comparison of existing protozoon and highly differentiated 

 adult animals. In what sense, then, can the ovum of a higher 

 vertebrate be said to correspond with the ancestral Amoeboid? 



m Quoted by Morgan, Evolution and Adaptation, p. 71. 



" Quoted by Montgomery. Analysis of Racial Descent, p. 184, from Lehrbuch der 

 Zoologie, 1888. 



'• Quoted by Montgomery, toe. oil. 



