238 



The Jol'rnal of Heredity 



this was true or not Dc Vrics began a 

 scries of carefully planned experiments 

 to demonstrate whether species may be 

 produced experimentally. These tests 

 and many suljsequent observations 

 demonstrated that species-formation is 

 not always a slow and gradual process, 

 but that new species may be formed at 

 a single step. 



These experiments have had great 

 influence in stimulating research in 

 genetics, not by the Darwinian method 

 of collecting facts, but by carefully 

 planned experiments with their proper 

 checks. De Vries' reputation, indeed, 

 will last longest not from his elaboration 

 of the mutation theory, which was 

 already suggested by Darwin, but by 

 his introduction of the experimental 

 method into the study of evolution. 

 To the worker in practical genetics the 

 experiments of De Vries also have great 

 value. By dealing with vast numbers 

 of plants or animals the breeder seeks to 

 discover the mutants, as De Vries called 

 the suddenly appearing new forms, 

 or cxce^^tional individuals, and produce 

 new and valuable races from them. 



PRESENT POSITION OF GENETICS. 



The new science of genetics holds 

 today a very prominent place among its 

 sister sciences. Around it are clustered 

 many great problems now occupying 

 the attention of thoughtful men, while 

 upon it is based the practice of the 

 producer of animals or plants to bring 

 forth better varieties and strains for 

 the use of mankind. Problems of 

 eugenics, furthermore, are receiving 

 wide consideration, and in order to be 

 sane and in accordance with the laws of 

 Nature, they must be kept close to the 

 foundation principles of genetics. 



The laws of heredity were applied 

 empirically by the shepherds of the 

 flocks and the tillers of the fields centur- 

 ies before their full imjjort was known. 

 Scientific and ])hilosoi:)hic minds have 

 long sought to soh-e the probk^ms 

 involved in the apparently simple 

 truths, "like begets like", and "the 

 jins of the fathers shall be visited upon 

 the children unto the third and fourth 

 generations." From the .sum t(jtal of 

 this knowledge, empirical and scientific, 

 practical and theoretical, has been 



evolved much of definite significance 

 concerning racial and individual devel- 

 opment. But the most important and 

 most attractive single contribution was 

 the mathematical formula of heredity 

 discovered by Gregor Mendel half a 

 century ago. It is not exaggerated to 

 speak of his discovery as Icadin? into a 

 new world, the very existence of which 

 was unsuspected before. 



"In research as in all business of 

 exploration, the stirring times come 

 when a fresh region is suddenly unlocked 

 by the discovery of a new key. The 

 conquest is easy and there are prizes for 

 all. We are happy in that during our 

 own time not a few of such territories 

 have been revealed to the vision of 

 mankind." "I do not dare to suggest," 

 says Bateson, "that in magnitude or 

 splendor the field of genetics may be 

 compared with that now being disclosed 

 to the physicist or the astronomer; for 

 the glory of the celestial is one and the 

 glory of the terrestrial is another. But 

 I will say that for once, to the man of 

 ordinary power who cannot venture 

 into those heights beyond, Mendel's 

 clue has shown a way into a realm of 

 nature which for surprising no\'elt>' and 

 adventure is hardly to be excelled." 



To Gregor Mendel, monk and abbott, 

 belongs the credit of founding the 

 modern science of heredity. Through 

 him there was brought into these 

 problems an entirely new idea, a fresh 

 conception of the nature of living things. 

 Mendel demonstrated by a carefully 

 planned series of experiments that 

 plants and animals are not indi\-isible 

 entities, but that every indi\-idual con- 

 tains an enormously large number of 

 smaller units, each separately heritable. 

 And furthermore, he demonstrated that 

 these units are transmitted in a definite 

 and regular manner. 



GREGOR Mendel's influence. 



The rediscovery of Mendel's Law 

 some fourteen years ago has led to a 

 com])lete change in our attitude towards 

 the ]:)roblems of variation, heredity and 

 evolution ; and the new method of study 

 thus introduced has rendered possible 

 a renewal of the attack upon these 

 problems with renewed vigor and with 

 remarkable results. 



