SELECTION IN PLANT BREEDING 191 



the country, and the individual who was responsible would deserve to be 

 ranked among the greatest benefactors of the commonwealth. 



This illustration serves to show something of the extent of the bene- 

 fits that may be confidently expected from the improvement of culti- 

 vated plants ; but the full extent of our rightful expectations is at least 

 ten per cent, increase in both quality and quantity of all the great 

 crops of the United States. In fact this is a very conservative forecast 

 based upon what has been accomplished in the past. Men like Haynes 

 with his " Blue stem " wheat and J. S. Learning with his " Learning " 

 corn have perhaps made an even greater percentage increase in the 

 value of the returns from the land upon which their productions have 

 been grown. Their results were obtained largely in the latter half of 

 the last century and even greater advances should be made in the fu- 

 ture. This statement is made because, in the last quarter of the nine- 

 teenth century, experimental biology was in the same relative position 

 in which chemistry stood in its beginning. During the century chemis- 

 try made wonderful advances; during this — the twentieth — century 

 experimental biology will make similar progress. And one of the first 

 and most important applications of the facts discovered will be to 

 guide and direct man in producing new plants and animals by more 

 direct and certain methods. 



When one speaks of producing new plants, however, he should not 

 be misunderstood. Man has not yet actually produced new variations 

 (although the time may come when even this is possible) ; he simply 

 works with the variations which have occurred through natural causes 

 of which little is known. The isolation of a varying plant and from it 

 the production of a variety, or the combination of desirable characters 

 from one strain with other desirable characters from different strains, 

 comprises the total aim and desire of the plant breeder. The idea is 

 simple ; to put the idea into practise successfully is often a tedious and 

 difficult task. 



As in hybridization the ease with which results can be obtained by 

 selection depends largely upon flower structure. In selection, how- 

 ever, the relative facility with which artificial cross-pollination can be 

 accomplished is of small importance. What one wishes to know is 

 whether cross-pollination or self-pollination takes place naturally. 

 Practically all plants are occasionally cross-fertilized naturally, and 

 many of them have devices whereby they are nearly always crossed ; but 

 we are coming to see that cross-fertilization is not as essential to plant 

 life as Darwin endeavored to prove in his " Cross- and Self-fertilization 

 in the Vegetable Kingdom." Wheat, for example, is almost always 

 self-fertilized; yet it has kept its vigor for thousands of years. The 

 importance of this fact to the selectionist is easily seen. If seed from 

 several varieties of wheat is mixed and planted, each variety remains 



