334 ELEMENTARY STUDIES IN BOTANY 



for each school to secure a set of these bulletins dealing with 

 the prominent crops of the vicinity. 



37. State Experiment Stations. The same sort of work 

 and the same free distribution of information is going on at 

 the various State Agricultural Experiment Stations, and the 

 bulletins from the station in its own state should certainly 

 be obtained by each school. 



Although the national government and the state govern- 

 ments and the seed firms are all at work on the problems 

 of plant-breeding, so that the cultivator of plants may take 

 their results and use them, yet the intelligent cultivator 

 should know something of the methods and possibilities of 

 plant-breeding. This knowledge will at least give him a 

 more critical j udgment in reference to the claims made by the 

 practical plant-breeders. 



38. Mass culture. The oldest method of plant-breeding 

 is called mass culture, a method which has done much in 

 securing improved races of plants. It may be explained by 

 using wheat as an illustration. The plant-breeder selects 

 some feature of the wheat he wishes to improve ; for example, 

 its yield. He goes through a wheat field and selects the indi- 

 vidual plants whose heads bear the largest number of grains. 

 The grains from these selected plants are saved for seed, and 

 in the next season they are planted and produce a crop. 

 The plant-breeder goes through the new field and again selects 

 the best individuals, and their grain is saved for seed. This 

 selection goes on year after year, and each succeeding year 

 shows a somewhat larger yield than the year before. Pres- 

 ently by this method of " continuous selection " the larger 

 yield reaches a standard and a steadiness that enables the 

 plant-breeder to announce an improved race of wheat, that is, 

 a race improved as to its yield. 



This method of plant-breeding has certain disadvantages 

 that are obvious. It requires a great deal of time and labor, 

 and when the improved race is put into the hands of an 



