ORGANIC EVOLUTION AND THE SIGNIFI- 

 CANCE OF SOME NEW EVIDENCE 

 BEARING ON THE PROBLEM* 



I. 



The biological problem recognized as having the great- 

 est fundamental importance at the present period is that 

 problem of evolution relating to the means by which the 

 heritable characters differentiating various organisms 

 from one another were first called into existence, or 

 granting the validity of the gene hypothesis and speaking 

 more concisely, how hereditary character-forming genes 

 have originated in the process of evolution. That the 

 diverse forms of life found upon the earth are only to 

 be explained as the result of organic evolution, is a prop- 

 osition which scarcely needs be mentioned at the present 

 period in the history of science, at least so far as indi- 

 viduals endowed with minds reasonably logical in evalu- 

 ating evidence are concerned. It is not evolution as a 

 process going on in the world which is being particularly 

 questioned nor the general method by which characters 

 once having originated are inherited, but the particular 

 method by which heritable characters first arose. 



The purpose of the essay here presented is threefold. 

 First, that of pointing out the unsatisfactory nature of 

 much of the earlier evidence as a basis for sound general- 

 izations in connection with a clear understanding of evo- 

 lution. Second, that of calling attention to the serious 

 shortcomings of modern methodology in throwing light 

 on the causative factors of evolution. Third, that of 

 presenting some new evidence somewhat unique in its 

 nature, based in part on preliminary experimental work, 

 to the effect that the environment acting through long 

 intervals of time may impress characters upon an organism 

 which become unalterable by reversal processes. 



*Reprinted from The American Naturalist, vol. 5 2 (1918), pp. 521-547. 



