DIRECT AND INDIRECT SELECTION 209 



the ancestral type. It further follows that (as regards each char- 

 acter) ancestors are represented by the individual, not en masse> 

 but in orderly succession. The so-called contributions of ancestors 

 are nothing other than reversions, that is to say, failures to 

 recapitulate the life-history beyond the points reached by the 

 ancestors, or else the reappearance of hitherto dormant characters. 

 The truth of recapitulation, though admitted by the majority of 

 biologists, is universally ignored when theories of heredity are 

 formulated. Biologists found their belief in recapitulation solely 

 on very uncertain and fragmentary embryological evidence. They 

 have not realized that, given facts which are admitted to be true, 

 any method of development other than by a recapitulation of the 

 life-history is unthinkable. This failure, together with the failure 

 to distinguish the true nature of, the true distinction between, 

 innate and acquired characters, has been in the past a principal 

 obstacle to a scientific systematization of the facts of heredity, a 

 main source of error, confusion, wild speculation, and endless 

 controversy. 



344. Evolution (i.e. adaptation) depends as much on retro- 

 gression as on progression. Direct Natural Selection is concerned 

 almost exclusively with progression. Only seldom is it a cause of 

 retrogression, which, with rare exceptions, occurs only on cessation 

 of selection, and is due to the general tendency to reversion i.e. 

 the general tendency to abbreviate rather than to prolong the life- 

 history. In the last analysis, however, this tendency is itself due 

 to the Natural Selection of strains that possess it in the right 

 degree. Retrogression planes away all redundancies, all useless 

 variations and structures that have lost their utility. 



345. The function of conjugation is to blend parental char- 

 acters. The average experience of the race is thus substituted 

 for the special experience of the individual. Moreover, in each 

 blend retrogressive (i.e. the more ancient) characters tend to be 

 prepotent over progressive (i.e. less ancient) characters. The 

 effect of this blending, therefore, is to bring about the more or less 

 rapid retrogression of useless characters a retrogression which is 

 only checked or reversed by selection. Sex, therefore, is as much 

 a selecting agency as Natural Selection. Since every gradation 

 occurs between equal blending of parental characters and the 

 exclusive inheritance of the character of one parent only, it is 

 convenient to class even exclusive inheritance under the head of 

 blended inheritance. There is no such thing as alternative 

 inheritance ; there is only alternative patency and latency. When 



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