280 



The Pedigree Families. 



might give the impression that mutants are much more 

 numerous than they really are. In this culture there 

 were as a matter of fact 60 mutants among 2070 seed- 

 lings; that is — about 3 %. If I had wanted to show this 

 proportion in the photographs each one could not have 

 shown more than one mutation at the most. But the mu- 

 tants are very irregularly scattered amongst the other 



Fig. 48. Mutation in the /a?a-family (1900). Origin of O. 



albida, O. oblouga, O. ruhrinervis and 0. subovata. The plants 



are arranged in 3 rows as follows : 

 Upper row: Lam. Lam. lata Lam. ruhrinervis 



Second row: lata albida albida lata Lam. 



Third row: Lam. subovata albida oblonga Lam. 



seedlings and I naturally chose groups in which there 

 happened to be a lot of them. The most abundant mu- 

 tation in this experiment as in others was 0. alhida. 

 On Plate IV three are to be seen : the third plant in the 

 upper row is one ; another is the second plant in the 

 third row; another the first plant (on the left) in the 



