24 PLANT-BREEDING 



ing from the main stem of the Lamarckiana in 176 of the 

 14,000 seedlings. It was called oblonga. All these forms 

 were purely self- fertilized and yielded uniform races without 

 reversion to the original evening primrose of Lamarck. 



With the exception of the gigas, which has not been re- 

 peated in this pedigree, all the types spring more or less regu- 

 larly, in every generation, from the pure parent stock. As 

 often as they were purely fertilized they produced constant 

 strains, which, however, did not differ from the previous races 

 of the same name. 



Besides these, quite a number of minor mutations have 

 occurred in my cultures. Some of them died in early youth or 

 before flowering ; others were barren of pollen, or not capable 

 of fertilization, and yielded no seeds. Some were too weak 

 for the conditions of my garden and succumbed, sooner or 

 later, mostly during the winter after their germination. The 

 range of mutability of this primrose, evidently, has not been 

 exhausted; and even during last summer a wholly new type 

 made its appearance. 



A main point in these observations is that the mutations 

 occur suddenly, without preparation and without interme- 

 diates. Nothing indicates on the normal plants what their 

 seeds will produce, and there is even no means at all by which 

 to decide beforehand whether the fruit of one individual, or 

 one branch, will be richer than any other in the production 

 of mutations or of some distinct mutant. The distribution 

 of mutating seeds seems to depend simply upon chance. Nor 

 are there intermediates. Each mutant is as good a repre- 

 sentative of its type as its progeny will be; it does not need 

 any special cultivation or improvement to reach the full dis- 

 play of its character. No half-mutants are seen, neither 

 from seed of the parent form nor from seed of the first mu- 

 tant itself. These sharp distinctions clearly indicate that 

 each mutation consists of the production of a single unit- 



