No. 7. DEPARTMENT OF AGRICULTURE. 219 



spring are never precisely like their ancestors. This is known as the 

 "Law of Variation." 



It may seem as we read them, one after the other, to be somewhat 

 paradoxical, but I think^ on a moment's reflection, it will be seen that 

 it is perfectly plausible that the law of heredity and the law of varia- 

 tion can both be in force at the same time. You may ask if the law 

 of heredity is in force, how can the law of variation be also in force? 

 We know there are animals that produce after their kind. We know 

 that rodents have not changed at all since we can remember^ or the 

 change has been so slight that we do not notice any change, but the 

 law of variation comes in because we know that two rodents are not 

 alike. They distinguish one from the other. We know that the 

 rodents recognize each other. They know the dilference and we 

 know that they know it. Squirrels in the forest recognize each other 

 and so with other wild animals; they recognize each other. 



III. Vastly more animals are produced than are needed for breed- 

 ing, and only those having the highest aggregate of good points 

 should be used to breed from. This is called "Selection." 



IV. By training, environment and selection in pairing, the form 

 may be modified and the relative value of the various points be 

 changed so as to better suit the uses or the fancy of the breeder. 

 This is called ''Breeding to Points." 



V. By breeding to points, the characters may be increased beyond 

 what they were in the ancestry. This is called "Improvement of 

 Breeds." 



VI. The more uniform the ancestry in character and the more re- 

 stricted in number, the more uniform and certain the resulting de- 

 scendants. The converse holds equally true. 



To the first two I wish to call your special attention. We rqust 

 accept as fundamental propositions the self-evident truths or axi- 

 oms in building our laws that we recognize as principles of breed- 

 ing, and I have selected for special discussion the law of heredity 

 and the law of variation, and if possible to discuss the effects ot 

 crossing or of mating the unlike in relation to these two laws. 



It is a matter of common observation that the law of heredity per- 

 vades all nature; the continuity of the species depends upon it. It 

 must be so for our species of wild animals and plants are fairly con- 

 stant. Without this law the perpetuation of these could not be ac- 

 complished, and it is thought that this was the first law that men 

 recognized — that it was the first recognized law of stock breeding, 

 and from the earliest histories that we have we are led to believe 

 that the ancients first recognized the law in their endeavor to 

 claim some superiority from relationship — by claiming a relation- 

 ship to a superior individual. They undoubtedly did that, 



