Repeated Mutations Due to the Same Causes. 463 



The facts, summarized in this and tlie previous sec- 

 tion, of the repeated reappearance of the mutations ob- 

 served in my cultures evidently admit of one explanation 

 only, viz., that the potentiality for each mutation is pres- 

 ent in a latent condition m the apparently normal indi- 

 viduals in my cultures. 



Let us take as an example the Lamarckiana-id.m\\y 

 (p. 224), of v^hich I have grov^n a great number of suc- 

 cessive generations. The first sow^ing gave two mutations 

 {lata and nanella) ; the following generation gave them 

 again, and one other besides. The seeds for this second 

 sowing were gathered from 6 seed-parents which had 

 flowered far away from other Oenotheras and therefore 

 can only have been fertilized by one another. They were 

 obviously chosen without any indication whether they 

 would be more likely to produce mutations than the re- 

 maining individuals of the first generation. That these 

 six seed-parents reproduced the same mutations as their 

 parents proves that there existed in them some heritable 

 character in a latent condition. 



The same is true of subsequent generations and of 

 the other families in my cultures. Each time the same 

 mutations arose from apparently normal individuals. The 

 capacity for giving rise to these must therefore have been 

 inherited in the latent condition. 



If a latent capacity of this kind is not assumed the 

 following three facts become absolutely inexplicable. 



First, the circumstance that the same mutation ap- 

 pears in the same crop in two or more of several indi- 

 viduals, whether the crop arises from the seeds of one 

 or several seed parents. 



Secondly, the oft cited fact (Part II, p. 272 etc.) 

 that the appearance of mutations seems to depend almost 



