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1916] LAWS OF PLANT AND ANIMAL BREEDING. 51 



2. The law of variation says that all plants and animals tend to 



vary. 



3. The law of selection says that plants and animals are im- 



proved by selection which may be natural, social, or intel- 

 lectual. 



4. Galton's law of averages may be stated as the fact that while 



a few individuals are superior and a few are inferior, most 

 are nearly average individuals. 



5. DeCandolle gave us the law that a plant should not be moved 



more than one degree of latitude at a time unless we wish 

 to change its nature. 



6. DeVries* law of Mutations is stated as the fact that occasion- 



ally there appears a superior individual which if prepotent 

 is called a mutant. 



7. The most complex and hence the most helpful of all the laws 



for people who have mastered them, are the Mendelian 

 laws. These are named under three terms, the terms, 

 " three to one, dominant, and recessive." 



Let us examine for a minute law number one. This law says 

 that similar tends to produce similar. We used to say that like 

 produces like. Then we discovered that no two are alike. Then 

 the scientist working with the Mendelian Laws discovered that 

 the changes are not the addition of things that are new but the 

 recombination of old factors. But recently the Carnegie men and 

 others have verified the Darwin belief that there is progressive 

 variation, that is, variation that is accumulative and is inheritable. 

 But I leave the wrong impression if I do not tell you that one of 

 the big problems in the world of science today is the problem of 

 whether there is a progressive, accumulative variation which is 

 inherited by the young. For agricultural purposes it is sufficient 

 to say that similar tends to produce similar. 



The second law^ has since the days of the belief in evolution, 

 come to be very generally accepted as the basis for our belief that 

 there is progress. If there is constant variation and if the varia- 

 tions are inherited, and if the fittest survive there will be progress. 

 The world was long in coming to this belief and I fear that 

 many farmers do not yet fully believe it. However, variation 



