Periodic Mutations 713 



the physicists are harmonized on the ground of 

 the theory of mutation. 



The steps may be surmised to have never been 

 essentially larger than in the mutations now 

 going on under our eyes, and some thousands of 

 them may be estimated as sufficient to account 

 for the entire organization of the higher forms. 

 Granting between twenty and forty millions 

 of years since the beginning of life, the intervals 

 between two successive mutations may have 

 been centuries and even thousands of years. As 

 yet there has been no objection cited against this 

 assumption, and hence we see that the lack of 

 harmony between the demands of biologists and 

 the results of the physicists disappears in the 

 light of the theory of mutation. 



Summing up the results of this discussion, we 

 may justifiably assert that the conclusions de- 

 rived from the observations and experiments 

 made with evening-primroses and other plants 

 in the main agree satisfactorily with the in- 

 ferences drawn from paleontologic, geologic 

 and systematic evidence. Obviously these ex- 

 periments are wonderfully supported by the 

 whole of our knowledge concerning evolution. 

 For this reason the laws discovered in the ex- 

 perimental garden may be considered of great 

 importance, and they may guide us in our fur- 

 ther inquiries. Without doubt many minor 



