THE MENDELIAN PHENOMENA 19 



observed to occur in the first hybrid generation, nor 

 do they occur in any subsequent generation derived 

 from the cross. It is perhaps not surprising that 

 the dwarf which disappears altogether in the first 

 hybrid generation should reappear in the second. 

 And although we have said that the true breeding 

 of the dwarf when it does reappear is roughly what 

 we should expect from one point of view, there is a 

 point of view from which it is the very opposite of 

 what we should expect. The fact of the dwarfs in the 

 second hybrid generation breeding true means that 

 they are entirely free from the taint of tallness in spite 

 of the fact that both of their parents and half of the 

 rest of their ancestors were tall. A dwarf occurring in 

 the second hybrid generation — an " extracted " dwarf 

 as it is called — is as pure a dwarf as the pure parental 

 dwarf with which the cross was made, not only in 

 its external characteristics, but also, what is more 

 remarkable, in its breeding properties. The true 

 breeding of one-third of the tails in the second hybrid 

 generation is not quite such a remarkable fact, because 

 in this case their parents at least bore the tall 

 character ; but it is remarkable that these tails 

 should exhibit no trace of the dwarf character of 

 half the grand-parental generation and of half the 

 ancestry behind that point. 



When we come to consider the fourth and further 

 hybrid generations we shall find that the results come 

 to difier still more widely from what current 

 notions of heredity would lead us to expect them 

 to be. 



