The Laws of Mutation. 253 



varieties for the very reason that I have been able to ob- 

 serve their origin.^ 



IV. New elementary species appear in large numbers 

 at the same time or at any rate during the same period. 

 Scott's palseontological results have led him to conclude 

 that species-forming variability, or, as he also calls it, 

 mutability must appear simultaneously in large groups 

 of individuals and that the causes of these changes have 

 probably been working through long periods of time.^ 



The palaeontologist investigates the problem of the 

 origin of species only in broad outline. It is the experi- 

 mental physiologist who deals with the separate individ- 

 uals themselves and with their posterity, of whom not a 

 millionth part would ever be preserved in the fossil state. 

 We have no right therefore to expect more than a general 

 agreement between the conclusions attained by these two 

 lines of investigation. 



And when we do find such agreement, as we do in the 

 present instance, I think it is extremely desirable that it 

 should be put on record. 



Amongst the species which have arisen in my experi- 

 mental garden Oenothera gigas has only been observed 

 once. The others appeared every, or nearly every, year 

 in varying, and often, indeed, in considerable numbers. 

 More than 800 individuals of the seven new species we 

 have described arose independently from one another 

 from the Laniarckiana-isimiiy. And as about 50,000 

 plants were cultivated during this period of time the 



^Fortunately, as a matter of fact, this has not been the case 

 (Note of 1908). 



^W. B. Scott, On Variations and Mutations. Amer. Journ. Sci.. 

 3d Ser., Vol. 48, No. 287, Nov. 1894. See p. 2>72>- '"Forces both ex- 

 ternal and internal similarly afifect large numbers of individuals." 



