3 



PLANT-BREEDING 



Fig. n. Poland wheat 

 (Triticum poloincum). 



increase of the unavoidable admix- 

 tures of little worth. 



During the middle ages no records 

 seem to have been made as to the 

 methods of cultivating cereals. Wheat 

 and barley had been the grains of the 

 ancients; to these, oats have been 

 added during the period of the lake- 

 dwellings, and rye is the most recent 

 of the European species, having been 

 introduced into Europe during the 

 middle ages. Corn, of course, is of 

 American origin, and has been con- 

 nected with the development of the 

 ancient American cultures, quite in 

 the same way as the grains were con- 

 nected with those of the old world. 



The idea of improving these valu- 

 able crops seems to have presented 

 itself only after the beginning of the 

 last century. Different principles 

 were set forth, as soon as the possi- 

 bility of improvement had once been 

 ascertained. Some of them were of 

 a more practical nature, resting on 

 direct observation, but others relied 

 on theoretical views concerning the 

 influence of environment on the qual- 

 ities of living organisms. Both of 

 these main directions have attained a 

 high degree of significance in agri- 

 cultural practice as well as in the 

 purely scientific discussions concern- 

 ing the origin of species in nature. 



