December 29, 1911] 



SCIENCE 



905 



on a law actually known to hold for those 

 organic processes that are most favorable 

 for study with relation to such laws. Can 

 a stronger statement be made for the effi- 

 ciency of selection or of any other factor, 

 as producing and modifying the character- 

 istics of organisms 1 There was a time, not 

 distant, when the biologist hardly dared 

 speak of the possibility of the inheritance 

 of acquired characters in any sense, be- 

 cause experimentation was unable to dem- 

 onstrate its occurrence. But after learning 

 the rules for the interweaving and transfer 

 of characteristics in successive generations, 

 we find as much difficulty in showing ex- 

 perimentally that selection modifies hered- 

 itary characters as we do in showing the 

 inheritance of acquired developmental 

 habits, so that the two ideas now stand 

 once more on the same footing. This revo- 

 lutionary change in the relation of these 

 two possible factors is one of the important 

 fruits of the recent development of genetic 

 science, with its demonstration that most 

 of what had been considered a productive 

 action of selection was in reality not such. 

 If we are reduced once more to judging 

 the two ideas by their relative value for 

 explaining what we find to exist, habit for- 

 mation in development does not suffer by 

 comparison with selection. 



If the formation of developmental habits 

 really occurs, then the fact that each of us 

 has taken part in the development of so 

 many men and so many women, and even, 

 in former times, in the development of so 

 many creatures not yet men and women, 

 helps us to understand many of our im- 

 pulses, revealed suddenly and unexpect- 

 edly to ourselves; helps us realize why we 

 feel that the character and tastes we have 

 manifested in our lives form only one of 

 the types of character that we might have 

 displayed; that perhaps we have displayed 

 in times past. 



But however it be with this particular 

 point, I have lived, like the infusorian, 

 in unbroken material continuity for un- 

 counted ages; if the phrase "potential 

 immortality" means anything for the in- 

 fusorian, it means exactly the same for 

 me, so far as we can judge from past 

 history. 



But what then of the future? We 

 have each a singular wish to trace our 

 existence not so much backward as for- 

 ward; certainly no other problem of gen- 

 etics has commanded such universal in- 

 terest as that of immortality. 



Many non-scientific theories of immor- 

 tality have held that we do continue to 

 exist in later generations, in the form of 

 human beings or in other forms, but that 

 we do not remember our previous lives. 

 This last proviso is a relapse into science; 

 it is an attempt to reckon with the facts, 

 for we each observe, upon inspection, that 

 we do not remember a previous existence. 

 What difference would there be between 

 reincarnation without recollection of our 

 previous experiences — and the actual re- 

 living of our characteristics when a por- 

 tion of our body develops anew the char- 

 acter and traits that now exist in us? If 

 you are a reincarnation of some former 

 individual without the remembrance of his 

 experience — and / am a re-development of 

 the characteristics of some former indi- 

 vidual from a piece of his body — what 

 pragmatic difference, what difference that 

 experiment or experience could detect, 

 would there be between the two cases? 



Thus the fact that we re-live in posterity 

 would seem to constitute all that can be 

 meant by immortality without recollection 

 — if we reproduced as the infusorian does, 

 each for himself, each giving rise to indi- 

 viduals like himself. 



But just here we meet that tremendous 



