Application of Biological Principles to Plant Breeding 137 



shown the scientific basis for Vilmorin's method of selection, 

 which before was not in general use, the statement is largely 

 true. Yet they have been of inestimable practical value. 

 They are time savers. In hybridization, one no longer 

 grows large quantities of first generation hybrids and small 

 quantities of second generation hybrids, for he knows that 

 it is in the second generation that the desirable recom- 

 binations of characters will occur. In many cases he can 

 even predict with some accuracy the exact number of second 

 generation individuals which it will be necessary for him 

 to grow to obtain the desired result. And even when this 

 cannot be done he knows that the blended characters of 

 the first hybrid generation do not mean that he has failed 

 to attain his object. It is simply a matter of growing large 

 numbers in the second hybrid generation that insures 

 success. Furthermore, the plant breeder has a means at 

 hand to show what characters are heterozygous and there- 

 fore unfixable. He therefore no longer wastes time in 

 striving for a pure strain of a heterozygous t>'pe such as the 

 Blue Andalusian fowl. Nor does he still regard the appear- 

 ance of "rogue" plants in his nursery beds as a necessary 

 affliction of Providence. He has learned that they are 

 simply recessive segregates and can be prevented by prop- 

 erly protected hand-pollinations. 



In the field of selection the new ideas are still more 

 economical of time. To the belief that faith and continu- 

 ous selection toward an ideal would produce any desired 

 result has succeeded the idea that nature alone produces 

 variations and that man's duty is to be alert to grasp their 

 possibilities and to make the most of them. No longer is 

 it believed that many generations of work are necessary 

 to purify a commercial variety of plants from undesirable 



