Mutations in Nature. 301 



seemed to me to be an indispensable preliminary. Hitherto 

 this phenomenon had not been observed at all, in the nat- 

 ural state. I had to postpone the plan of determining 

 the causes of these processes. Then it must be remem- 

 bered that our knowledge of the effects of crossing was at 

 that time practically nil\ and such knowledge is an ab- 

 solutely essential condition for an experimental investi- 

 gation of the phenomenon itself. It was imperative that 

 the laws of hybridization (especially those to which the 

 Oenotheras conform) should be determined first. 



For these reasons I have postponed an investigation 

 into the causes of mutation until these preliminary prob- 

 lems were well on the road to solution. 



Tliere are two ways of studying mutation in the field. 

 The first is to look for and collect the mutants in the 

 place where the parent grows. The second is to collect 

 the seed in the field and to grow it under as favorable 

 circumstances as possible. 



It will be immediately evident what an incomplete 

 method the first one is, and how much superior to it is 

 the second. For the mutation must obviously already 

 liave taken place in the seed ; all that germination does 

 is to bring it before our eyes. Consider what a vast 

 number of seeds perish during the first few days after 

 germination, or even during the first weeks, when they 

 are left to nature ; especially in the case of the weaker 

 seeds, which perhaps may contain the greater number of 

 the mutants. An average plant of Oenothera La- 

 marckiana, growing wild, often has over a hundred fruits 

 and each fruit contains from one to two hundred seeds. 

 Therefore even in times of rapid multiplication it is only 

 a very small percentage of the seedlings which grow to 



