AGRICULTURAL BOTANY 165 



the stock must be cut off in order to stimulate the 

 growth of the bud. 



Ring budding is sometimes performed in the spring 

 on thick-barked trees, like the hickory. This consists 

 in removing a narrow strip of bark nearly around the 

 stock and inserting therein a strip of the same size 

 containing a bud, then binding it in place. 



Plant Breeding. Creative force manifests itself 

 in an infinite variety of forms and qualities, no two 

 plants, no two animals being exactly alike, either in 

 appearance or in characteristics. This lack of uni- 

 formity in the individual plants in a field, for instance, 

 is responsible for a low yield of inferior quality, for if 

 all of the plants in the field were uniformly of the same 

 type as the best plants, the yield and value of the crop 

 would be greatly increased and the expense of handling 

 the crop would be reduced, thus doubly adding to the 

 grower's profits. 



Problems of Plant Breeding. One of the most 

 important and most difficult problems the farmer has 

 to solve is how to breed plants so as to bring up the 

 average of the crop to that of the best individual plants. 

 In the case of those plants which are partly or wholly 

 self-fertilized, that is, fertilized by pollen from the 

 same flower or plant, such as wheat, oats, barley, and 

 tobacco, the problem is not so difficult to solve as with 

 plants that depend upon cross-fertilization, such as 

 corn and hemp. 



The problem presents three phases : 



1. How can variations from the parent type be 

 produced ? 



2. How can selections of the best types be made ? 



3. How can the new types be made to reproduce 



