CEREAL ADAPTATION AND ASSOCIATION 293 



cured in seed of the smallest plants from localities where 

 the plants are commonly large; (3) on the other hand, 

 for large plants, seed of the largest individuals where 

 dwarfness is common and forced by the environment is 

 best ; (4) for earliness, usually seed of spring cereals from 

 the north and seed of winter cereals from the south are 

 best, with apparent exceptions. 



315. Effects of environment. The fact that com- 

 mercial varieties will change their characteristics on being 

 grown in a new and different environment is well estab- 

 lished. A variety as ordinarily observed is a mixture. 

 It is easy to see how the individuals better able to resist 

 severe weather conditions will survive, and the weaker ones 

 drop out, thus changing the complexion of the variety as a 

 whole. Pure-bred varieties are not affected to so great 

 an extent in the same time, but even these may be 

 modified after a long period, as in the case of the Swedish 

 Select oat (312). 



316. Environmental experiments. Until recent years, 

 very little investigation has been made in this line. Be- 

 ginning in 1907, the United States Department of Agri- 

 culture, through the Office of Cereal Investigations and 

 Bureau of Chemistry, conducted experiments for nine 

 years in Maryland, Kansas, Texas, South Dakota, and 

 California, to determine the effects, if any, of changes of 

 climate and soil on the wheat plant. Two series of ex- 

 periments were made with wheat, one in which seed 

 every year from each of three points in different states, 

 was sown at the other two points, and another in which 

 soil from each of three states (Maryland, Kansas, and 

 California) was transported to points in the other two, 

 and home-grown seed each year sown on the three soils 

 at the same point. The results of these two series of 



