138 THE LESSON OF EVOLUTION 



and may not be able to vary so readily as the newer 

 species. 



I must once more point out that, if it is difficult to 

 feel sure about any character in a living animal 

 being due to physiogenesis, it must be far more 

 difficult to form an opinion about fossil animals, of 

 which we know nothing except their shells or skele- 

 tons. And yet there are several naturalists in the 

 United States who find no difficulty at all, but write 

 about the acquired characteristics of fossil animals 

 with the greatest confidence. 



Transmissible variations may be preserved either 

 by selection or by isolation. The first of these 

 modes accumulates variations as well as preserves 

 them ; but isolation is a mode of preservation only. 

 And if the variations are to increase, it must be by 

 definite variation acting as the accumulator. 



Organic Selection. In 1896 Professor H. F. 

 Osborn, 33 Professor J. M. Baldwin, 34 and Principal 

 Lloyd Morgan 35 independently pointed out that indi- 

 vidual modifications, due to external conditions, 

 would help to keep those individuals alive, and so 

 preserve generation after generation until modifi- 

 cation became transmissible and attained a selection 

 value ; after which it would be preserved by natural 

 selection. 



Professor Osborn thus explains his idea. " Onto- 



33 " A mode of Evolution requiring neither Natural Selec- 

 tion nor the inheritance of acquired characters." Trans. 

 N. Y. Acad. Sciences, March and April, 1896. 



34 " A new factor in Evolution." Am. Nat. June and 

 July, 1896. 



" Habit and Instinct," 1896, p. 312, ff. 



