ON THE SMALL GRAINS 



nor short but intermediate; and if a wheat that 

 ripened early was crossed with one that ripened 

 late, the hybrid offspring ripened their grain at 

 an intermediate season, later than their early 

 parent but earlier than their late one. 



Yet here again and this perhaps is most sig- 

 nificant of all there was segregation of characters 

 in the second generation along the usual Mende- 

 lian lines. That is to say, the first generation 

 hybrids that bore grain of medium length will pro- 

 duce offspring one fourth of which bear long grain 

 and one fourth short grain, the other half bearing 

 intermediate grain; and similarly the first genera- 

 tion hybrids that ripened their grain at an inter- 

 mediate season, produce progeny one fourth of 

 which ripened their grain early and one fourth 

 late, the other half ripening their grain at the 

 intermediate season. 



The importance of this observation is that it 

 shows that the Mendelian principle of the segrega- 

 tion and recombination of unit characters in sec- 

 ond generation hybrids follows the same rule 

 whether or not the characters show clear dom- 

 inance in the first generation. 



And if we look a little beneath the surface it 

 will appear that there are hundreds or perhaps 

 thousands of unit characters that for one reason 

 or another do not show the phenomena of dom- 



[65] 



