482 



THE AMERICAN NATURALIST [Vol. LI 



extending scarcely beyond the tip of the lemma and only 

 distinguishable by careful examination. As this awn 

 becomes weaker, it is produced nearer to the tip of the 

 kernel ; that is, the rib of the lemma which forms the awn 

 adheres to the lemma for a greater distance before aris- 

 ing as an awn. Among the wild and cultivated types of 

 oats the awns are either characteristically strong, weak, 

 or lacking altogether. In hybrids of these, however, the 

 awns may present all gradations between the awnless and 

 the very strongly awned types. It is usually possible,' 

 though, to classify the hybrids as having strong, interme- 

 diate, or weak awns. (See Figures I and II.) 



Methods of Study 

 The parent plants and first-generation hybrids were 

 grown in the greenlioux', and the x-cond and third gen- 

 eration hybrids were liiown in tlic lidd. In the case of 

 the first-generation hybrids, all of the spikclets on all of 

 the plants could })e stiidicil. With the tmich larger Fa, 

 however, it was found imjuacticahle t<» att('in[)t to study 

 all of the spikelets on a ])iant. The study was limited, 



