APPENDIX E 



253 



could be no planing away of the numberless useless variations 

 which occur during, and especially at the end of, the ontogeny, 

 nor of all those structures which, though useful during some part 

 of the phylogeny, became useless later. Without reversion, there- 

 fore, a species would soon become so burdened with useless 

 variations and structures as to be incapable of existence. 

 Reversed Selection could not cause the elimination of all these 

 useless and burdensome characters ; for no matter how burden- 

 some, and, therefore, worse than useless, they are in the aggregate, 

 separately they are so little burdensome that Reversed Selection 

 could not act. It could not act on them in the aggregate, for 

 this would mean that in some individuals they would be present 

 en masse, whereas they would be absent en masse in others ; and 

 this, we know, is not the case. Moreover, Reversed Selection 

 causes a retracement, not a lapsing of characters. It therefore 

 works at a double disadvantage as compared with ordinary 

 Natural Selection, and, as a consequence, can effect comparatively 

 little. No extensive examples of such retracement are, in fact, 

 known to us in Nature. Again, without retrogression, the re- 

 capitulation of the phylogeny in the ontogeny would be impos- 

 sible, and, for this reason once again, evolution would be 

 impossible. For, were there no retrogression, the prototypes of 

 the phylogeny would necessarily be reproduced exactly in the 

 ontogeny, and then the latter would be as elaborate, and almost 

 as lengthy as regards time, as the former. Moreover, the 

 prototypes of the phylogeny could not exist in the enormously 

 changed environment of the ontogeny. How, for instance, could 

 a gill- breathing animal, or any of the higher forms which in- 

 tervene b'etween them and man, exist in the uterus, in which 

 alone can exist those dim representations of the phylogeny that 

 constitute man's ontogeny ? 



It is this great change of environment, this close protection of 

 the individual in the uterus and afterwards, which has rendered 

 possible the evolution of man and the other higher animals. 

 Opportunity has thus been afforded to retrogression to plane away 

 innumerable characters which had become useless. The ontogeny 



