496 On the Latent Capacity for Mutation. 



multiplication of our Oenotheras between the years 1870 

 and 1886 (p. 266) was the cause of the appearance of 

 the premutation period and therefore the beginning of 

 mutability in this case. And this supposition agrees so 

 well with the little that we know about the origin of spe- 

 cies in general that it deserves attention, to say at least, 

 until definitely disproved.^ 



We may sum up the *¥oregoing in the generalization 

 that each jnutational period is initiated by a premutational 

 one, in which the new characters, which are to appear, 

 arise in a latent condition under the influence of external 

 causes. 



^Afterwards I found that seeds of Oenothera Lamarckiana from 

 other sources, especially from the strains of different nurseries, may 

 produce the same mutations. From this I conclude that the period 

 of mutation must be older than the occurrence in the field at Hilver- 

 sum, and probably as old as the introduction of the present strains 

 into European gardens, which was effected by Messrs. Carter & 

 Sons about i860 from seed, gathered in Texas. (See Berichte der 

 deutschen Bot. Gesellschaft, 1905, Bd. XXIII, p. 382. — Note of 1908.) 



