THE PREVENTION OF INBREEDING 127 



In such a breeding plat, it is necessary to take every pre- 

 caution to prevent the introduction of pollen from any other 

 corn. All of the corn produced on the row planted to ear 

 No. 25 would, of course, be inbred; that is, these ears would 

 naturally have been fertilized by pollen produced on plants 

 from the same ear. All of this corn would be discarded and 

 seed saved only from the detasseled rows. 



161. Inbreeding. One of the difficulties encountered in 

 this plan is the inbreeding which is likely to be brought about 

 by this close selection of corn. Professor Williams has 

 planned to overcome this difficulty by continuing his ear-to- 

 row tests year after year. He has worked out a system which 

 calls for four separate plats or fields of corn each year. The 

 first plat is devoted to the ear-to-row test. The second 

 plat, where the best ears, as shown by the ear-to-row 

 test of the previous year, are mated, is called the breeding 

 plat. The third plat is termed the multiplication plat. 

 This may be of any size desired. Here the seed produced 

 from the breeding plat of the year before is planted to obtain 

 enough seed for field use. The fourth plat is the regular field 

 of corn or general crop, the seed for which comes from the 

 multiplication plat. 



For this ear-to-row test which is conducted each year, 

 some of the best ears are taken from the general field, some 

 from the multiplication plat, and some from the breeding 

 plat. When it is thought that new blood must be brought 

 in from outside, selected ears of the variety with which one 

 is working may be obtained from other farms or other 

 breeders. By running all of these ears together in the ear- 

 to-row test and then selecting and mating together the high- 

 yielding ears each year, new blood can constantly be brought 

 in from ears of known yielding power. This "is the plan of 



