22 ELEMENTS OF AGRICULTURE 



single tuber, is the unit. The melon vine, and not the 

 single melon, should be chosen. The good melon may 

 have been the only one that the plant produced. 



Constant selection is necessary in order to keep any 

 of our farm crops or animals up to their present standard. 

 The breeder of pure-blood cattle who does not cull out 

 many individuals is certain to run the average down. 

 Our standard is the upper part of the curve of variation. If 

 careful selection is not made, we will tend to get back to 

 the average. 



Most of our plants and animals already exhibit more 

 variation than we desire. Uniformity is often as important 

 as an increase in the yield. A uniform herd of cattle is a 

 better indication of good breeding than is a variable herd 

 that may have some better individuals. Uniformity in 

 size, color, and general appearance is of more importance 

 in selling vegetables and fruit than is mere size or flavor. 



22. Testing Hereditary Power. Testing the power to 

 transmit the good qualities to the next generation is really 

 further selection. Good individuals often fail to produce 

 good ones. The best ears of corn have been selected for 

 many years, and great improvement has been made. 

 Much greater improvement would doubtless have resulted 

 if the hereditary power had been tested, as explained 

 in the ear-row test (Fig. 12). 



Dairy herds that have been carefully selected often 

 come to be made up of the descendants of one cow; usually 

 from a good cow, but not always from the best cow. It 

 is not enough that a cow be a good one; she should be the 

 mother of good cows. Fig. 9 shows a good example of 

 such a cow. On the left is Prilly No. 40082 who produced 



