No. 629] DABWIN AND HYBRIDIZATION 



551 



not increase the potency of transmission, or eliminate be- 

 yond question the liability to reversion. 



Darwin considered it doubtful whether, as was then 

 popularly supposed, the length of time during which a 

 character had been inherited, had any influence on its 

 fixedness, and concluded from the fact that when wild 

 species which have remained so for ages, are brought into 

 cultivation, they immediately begin to vary, that no char- 

 acter by long inheritance can be considered as absolutely 

 fixed (Ic, 2:56). 



In this work, more than elsewhere, Darwin devoted 

 himself particularly to the question of the meaning of 

 inheritance in hybrids. The question always demanding 

 explanation was the reason for the reappearance after 

 the first generation of a hybrid of a parental, or even of 

 an ancestral form, a phenomenon then called "rever- 

 sion," including, as Darwin says: 



race or species, has, at some former period been crossed, and a char- 

 acter derived from his cross, after having: disappeared durins:' one or 



Darwin, at the outset, merely comments on the result 

 of crossing as follows: 



In considering the final result of the commin2:ling of two or more breeds, 

 we must not forget that the act of crossing in itself tends to bring back 

 long-lost characters not proper to the immediate parent form (Ic. 

 2: 64). 



It was noticed that from three to eight generations 

 were usually re(iuired before a l)reed derived from a 

 cross comes to be coiiMdcrcl free from (laiiavr of rever- 

 sion. What ron.litiit.Ml \hr ur.u-Wuu'vy lu l>rin- about re- 

 version reinaiiio.l. 'out f.o- Mmd.-lV }r\ uinli^.-ovvrod 



in that ro.-ar.i i< wll cxoinpli liod bv Dai'uln'^ remark. 



