76 'APPENDIX. 



of the rejected individuals in the line of the Horses? 

 Certainly they should be forthcoming in far larger 

 numbers than the individuals lying directly in the 

 path of development, for by our very assumption the 

 latter were greatly in the minority in every generation. 

 Doubtless the question would be a proper one if our 

 eyes were sufficiently keen-sighted to assign the life- 

 value of the various minute differences that distinguish 

 the "better" from the "worse" individuals of every 

 generation. But this is a task which we can accom- 

 plish at best only with selective processes which are 

 artificially directed by ourselves, as in the case of 

 doves and chickens, and even there only with the ut- 

 most difficulty and only with reference to a single 

 characteristic and not with any species which to-day 

 exists in the state of nature. Picture, then, the diffi- 

 culties attending such a task as applied to the meagre 

 fossilic bones of prehistoric species, touching which the 

 richest discoveries never so much as remotely ap- 

 proach to the actual number of individuals that have 

 lived together for a single generation in the same hab- 

 itat. If the differences between good and bad in a 

 single generation were striking enough to be imme- 

 diately remarked as such in fossil bones, the develop- 

 ment of species would take place so rapidly that we 

 could directly witness it in living species. 



IV. REMARKS ON THE HISTORY OF DEFINITELY DIRECTED 



VARIATIONS. 



As to the attempt here made to apply the selective 

 process to the elements of the germinal substance (the 

 idioplasm) and thus to acquire a foothold for definitely 

 directed variation not blind in its tendency but pro- 



