80 THE SHORTER SCIENTIFIC PAPERS 



eliminating the remainder from reproducing, the corn 

 grower plants with a fatuous trust in providence that a 

 crop somewhat better or at least as good as the preceding 

 crop will be produced. If it is a type comparatively pure 

 the average may be maintained and the hope partially 

 realized, but the chances for retrogression are far greater 

 than for advancement, inasmuch as there is no means for 

 distinguishing a variation which will be transmitted with 

 equal or better results than in the preceding generation, 

 from one that represents a fluctuation due to nurture and 

 which is non-transmissible. Thus the apparently inferior 

 ear of corn will frequently produce a yield far better than 

 obtained from one which is perfection as graded by the 

 methods of the "corn show," and if from the same pure 

 race, the resultant crop will be at least as good. Artificial 

 methods of hybridization, which furnish an immediate 

 advancement in the succeeding generation, result in a gain 

 which is only temporary. The increased stimulus to 

 growth vanishes as a fluctuation. 



Thus it is quite evident that there exists a problem in 

 the evolutionary control of organisms even the partial 

 solution of which will mark an extraordinary advance- 

 ment not only for agriculture, horticulture, and animal 

 breeding, but also for society in general. 



II. 



The general results of the investigations bearing upon 

 the evolutionary control of organisms may be grouped 

 around the principles of Mendelism, the mutation theory, 

 and pure line breeding. 



The rediscovery in 1900 of the fundamental laws gov- 

 erning hybridization so brilliantly established by Mendel 

 in 1865, but unfortunately concealed in the obscure pub- 

 lications of the Natural History Society of Brunn, opened 

 an extraordinary field for experimental work. This has 

 already developed to vast proportions in connection with 

 both the results obtained and the speculations involved, 

 while the end is not in sight. 



The investigations of Mendel, now so familiar to all 

 biologists, and which may be mentioned somewhat in 



