568 Mutations 



great is tlie chance for a single individual to be 

 destroyed in the struggle for life? Hundreds 

 of thousands of seeds are produced by la- 

 marckiana annually in the field, and only 

 some slow increase of the number of specimens 

 can be observed. Many seeds do not find the 

 proper circumstances for germination, or the 

 young seedlings are destroyed by lack of water, 

 of air, or of space. Thousands of them are so 

 crowded when becoming rosettes that only a few 

 succeed in producing stems. Any weakness 

 would have destroyed them. As a matter of 

 fact they are much oftener produced in the seed 

 than seen in the field with the usual unfavorable 

 conditions ; the careful sowing of collected seeds 

 has given proof of this fact many times. 



The experimental proof of this frequency in 

 the origin of new types,.seems to overcome many 

 difficulties offered by the current theories on the 

 probable origin of species at large. 



VI. The relation between mutability and fluc- 

 tuating variability has always been one of the 

 chief difficulties of the followers of Darwin. The 

 majority assumed that species arise by the slow 

 accumulation of slight fluctuating deviations, 

 and the mutations were only to be considered as 

 extreme fluctuations, obtained, in the main, by a 

 continuous selection of small differences in a 

 constant direction. 



