292 Retrograde Varieties 



in each instance reverted to the varietal mark 

 of the white cross, and three-fourths (77.5^) 

 retained the dark heart. Once more the flowers 

 were self -pollinated and the visits of insects ex- 

 cluded. The recessives now gave only reces- 

 sives, and hence we may conclude that the varie- 

 tal marks had returned to stability. The dark- 

 hearted or dominants behaved in two different 

 ways. Some of them remained true to their 

 type, all their offspring being dark-hearted. 

 Evidently the latter had returned to the parent 

 with the active mark, and had reassumed this 

 type as purely as the recessives had reached 

 theirs. But others kept true to the hybrid char- 

 acter of the former generation, repeating in 

 their progeny exactly the same mixture as their 

 parents, the hybrids of the first generation, had 

 given. 



This third generation therefore gives evi- 

 dence, that the second though apparently show- 

 ing only two types, really consists of three dif- 

 ferent groups. Two of them have reassumed 

 the stability of their original grandparents, and 

 the third has retained the instability of the hy- 

 brid parents. 



The question now arises as to the numerical 

 relation of these groups. Our experiments 

 gave the following results : 



