278 



PLANT-BREEDING 



other conditions of soil or climate, or to comply with any 

 other wishes of agricultural practice, it is necessary only 

 to know the botanical marks correlated with the desired 

 qualities. On this basis individual plants may be singled 

 out, and after multipUcation through a few years, their 

 progeny will probably respond to the demands made, as 

 soon as the industrial quahtics themselves are investigated. 



Fig. 84. A. Spikelct of oat-grass {Avena elatior), showing a flower with 

 two palets, three stamens, and two stigmas (a), a flower bud (b), of 

 which only the palets are visible and the third or sterile flower (c). 



Some instances of correlations may now be presented. 

 Different elementary species of oats are distinguished by the 

 form of their panicles. Some are stiff with a firm principal 

 axis and erect branches. In others the axis is weak and the 

 branches droop. In some varieties they are widely spread, 

 but in others they all bend to one side. According to these 

 marks definite types have been distinguished, and in com- 



