Apbil 11, 1913] 



SCIENCE 



543 



pirieal methods depends on a gradual elim- 

 ination of those operations or practises 

 which do not accord with basic natural 

 laws. In the consideration of the science 

 and practise of breeding this has some- 

 times been forgotten. It is difficult to re- 

 member always that a law of nature may 

 be presumed to have been in operation be- 

 fore its discovery. If Mendel's law repre- 

 sents a real and fundamental law of na- 

 ture, as certainly appears to be the case in 

 the light of present evidence, it is quite 

 certain that it did not begin operation in 

 A.D. 1900. Whatever of success has been 

 attained during centuries past in the breed- 

 ing of improved strains of animals and 

 plants, must have been attained by methods 

 and practises which were not violently in dis- 

 cord with Mendelian principles. A nomad 

 Arab may never have heard of the prin- 

 ciple of segregation, but none the less he 

 had to reckon with the phenomenon in 

 breeding his horses. 



Looking at the matter in this way, the 

 reason is clear why the rediscovery of 

 Mendel's work and the brilliant genetic 

 researches which have followed did not 

 and could not have had any profound revo- 

 lutionary effect on the practise of the ani- 

 mal breeders' art. By years — even cen- 

 turies — of "trial and error" methods, 

 breeding practise has been brought into 

 rather close conformity with the basic laws 

 of heredity. The discovery of some of these 

 laws by the geneticist could not radically 

 change the breeder's way of attaining re- 

 sults. 



What then has the rapidly developing 

 science of genetics done for the breeder and 

 what can it do? Still looking at the mat- 

 ter from the standpoint of the practical 

 animal breeder, it must be agreed, I think, 

 that the chief contribution of recent dis- 

 coveries in the field of inheritance is that 

 they have brought to light and fairly es- 



tablished certain general principles which 

 enable him in greatly increased measure to 

 understand and interpret his methods and 

 his results.^ This may seem too mild a 

 statement of the practical value of genetic 

 science to the animal breeder. It undeni- 

 ably does lack the grandeur of the vision 

 sometimes opened out by the extension 

 lecturer in his zeal to inspire the farmers to 

 better things, and at the same time pave 

 the way to increased appropriations for his 

 institution. But to help one to understand 

 and to interpret is, after all, no mean 

 achievement. It signifies that, with much 

 economy of effort, the successful breeder 

 may dispense with the merely trivial and 

 unessential in his empirical methods, and 

 more directly and uniformly attain the 

 same or a greater measure of success than 

 before. To his less successful brother and 

 the beginner, it means a surer and more 

 rapid guide than the old tradition based 

 on empiricism. It is certain that the young 

 man starting owX, to-day to be a breeder of 

 fine cattle, of fine horses, of fine chickens, 

 will attain his goal much sooner if he 

 thoroughly understands the meaning of 

 those laws of inheritance associated with 

 the name of Mendel. 



The most important general principles 

 which the scientific study of genetics has 

 firmly grounded are, it seems to me, these : 



{a) That the fundamental basis of all 

 inheritance is to be found in the germinal 

 constitution of the individual rather than 



° This is of course to be understood as a general 

 statement. There are now a few specific instances, 

 and in time there will be more, where the geneti- 

 cist has been able to show the breeder precisely 

 how to attain a particular result in breeding com- 

 mercially for a particular quality, which result he 

 had only hitherto been able to obtain by chance. 

 In no such case, however, so far as I am aware, 

 has the new method been so essentially different 

 from former practise as to be fairly regarded as 

 ' ' revolutionary. ' ' 



