172 BOARD OF AGRICULTURE. [Jan., 



Mr. Manchester. Not more than three out of five show 

 any improvement on the dam. 



Prof. Shaw. You remember that we have been talking 

 about the law of variation. Now I suppose that explains it. 

 I hope that you are not going to tell me that your herd now 

 is not a pure bred herd, if you have been choosing pure bred 

 sires for twenty years. I hope you are not going to claim 

 that your herd is not as good as though they were pure bred, 

 I hope you will not say that. 



Mr. Manchester. I could pick out a great deal better 

 pure bred herd. 



Prof. Shaw. Of course, you knOw that breeding alone will 

 not do it. There must be careful selection. 



Mr. Manchester. If that theory of yours is correct, why 

 are not all of them an improvement on the dam? 



Prof. Shaw. Because of the operation of the law of varia- 

 tion. A man may be breeding from pure bred sires, and that 

 man may be breeding in the very best possible manner, and yet 

 probably one out of every three will not be as good. The prin- 

 cipal thing for a man to do in breeding that kind of stock is 

 to turn it off and save the best. There must be a constant se- 

 lection along with the improvement in breeding. 



Question. What is the cause of the law? 



Prof. Shaw. I could tell you better if I understood how 

 those animals were cared for. 



Question. Is there any danger in using a thoroughbred 

 sire after keeping him one or two years that he may not be 

 prepotent? He may look all right but, unfortunately, may not 

 be prepotent for reasons that cannot be seen. 



Prof. Shaw. That is a good thought. It is true, you may 

 get a sire that is not prepotent, and who may be purely bred. 

 There is another mistake that farmers make sometimes. They 

 sometimes get a pure bred sire that is prepotent, but he is an 

 inferior individual. He has prepotency of the wrong kind. A 

 sire of that kind is dangerous. You remember when I was 



