200 A Defence of Menders 



certain moment a certain gamete divided from its fellows in 

 a special and unwonted fashion ; or, though the words are 

 in part tautological, the reason why the union of two par- 

 ticular gametes in fertilisation took place in such a way that 

 gametes having new specific properties resulted*. No one 

 yet knows how to use the facts of ancestry for the elucida- 

 tion of these questions, or how to get from them a truth 

 more precise than that contained in the statement that a 

 diversity of specific consequences (in heredity) may follow 

 an apparently single specific disturbance. Rarely even can 

 we see so much. The appeal to ancestry, as introduced by 

 Professor Weldon, masks the difficulty he dare not face. 



In other words, it is the cause of variation we are here 

 seeking. To attack that problem no one has yet shown the 

 way. Knowledge of a different order is wanted for that 

 task ; and a compilation of ancestry, valuable as the 

 exercise may be, does not provide that particular kind 

 of knowledge. 



Of course when once we have discovered by experiment 

 that say, Telephone manifests a peculiar behaviour in 

 heredity, we can perhaps make certain forecasts regarding 

 it with fair correctness ; but that any given race or 

 individual will behave in such a way, is a fact not 

 deducible from its ancestry, for the simple reason that 

 organisms of identical ancestry may behave in wholly 

 distinct, though often definite, ways. 



It is from this hitherto hopeless paradox that Mendel 

 has begun at last to deliver us. The appeal to ancestry is 

 a substitution of darkness for light. 



* May there be a connection between the extraordinary fertility 

 and success of the Telephone group of peas, and the peculiar frequency 

 of a blended or mosaic condition of their allelomorphs? The con- 

 jecture may be wild, but it is not impossible that the two phenomena 

 may be interdependent. 



