466 On the Latent Capacity for Mutation. 



I regard this conclusion as thoroughly proved in the 

 case of the commoner species which appear in measur- 

 able proportions (e. g., 1% or 0.1%). Whether or no 

 it also holds good for the rarer ones or for those which 

 did not appear till late must be regarded as of no con- 

 cern for the present. 



But if the existence of this capacity in a latent con- 

 dition in 1886 is demonstrated by my cultures, it follows 

 that all or most of these new species existed in a latent 

 condition before that date. 



This latent capacity to mutate, i. e., to produce a 

 series of definite and identical mutations, is therefore 

 a heritable character in my Oenothera Lainarckiana. 

 The particular factor for every given mutation must ob- 

 viously exist separately. And it must be supposed that 

 the various mutations, although they belong to the same 

 group or period, are nevertheless independent of one 

 another. 



As far as observation goes, this potentiality is always 

 inherited by all individuals. Of course many sowings 

 have given no mutants, and in other sowings certain 

 mutants have been lacking. But this may always have 

 been the result of the smallness of the scale on which the 

 experiment was carried out (whether this was because 

 the available quantity of seed w^as insufficient or that a 

 small culture was all that was necessary for the imme- 

 diate object of the experiment). In larger crops all the 

 commoner mutants appeared as a rule. For large cul- 

 tures like these the seeds of four or even 10-20 seed- 

 parents were needed. In these cases I have always sown 

 the seeds from each parent separately and it has never 

 happened that no mutants appeared amongst the progeny 



