F. L. Engledow 105 



(B) Hexastichum x distichum {H. inerme). 



Consistent results have not been obtained. The extreme fluctuation 

 to which H. inerme is liable in response to climatic change no doubt 

 largely accounts for this lack of consistency. One fact of great interest 

 has, however, been established. In the F^, the combination 6-row- 

 awnless does not occur. The inter-relation between six fertile rows 

 and the absence of awns which this fact implies, has yet to be discovered. 



(e) Intermedium x distichum, i.e. (B) x (F). 



Several such ^g's were raised in the summer of 1919, but the 

 extreme drought of the early part of the flowering period produced 

 great fluctuation. The ears of the single plant differed markedly among 

 themselves in some cases. It seems that here, too, a 1:2:1 ratio is 

 likely to be found, but the complete F-^s of 1920 will have to be awaited 

 for a confirmation of the anticipation. 



(^) Intermedium x decipiens, i.e. (B) x (G). 



Crosses between H. gymnospermum (awned, black, decipiens) and 

 H. Haxtoni (typical intermedium) indicate that the F^ consists of the 

 two parental types, and a heterozygote type. Sorting is too difficult to 

 give reliable proportions. The allelomorphism of (B) and (G) is not 

 therefore properly established. 



(17) Intermedium x distichum (H. inerme). 



Cf. (8) above. Here too emerges a fact of some interest. The pro- 

 portion of awnless types is extremely low. The awn is subject to very 

 great fluctuation, e.g. from ear to ear of a plant, and Fs's will be necessary 

 before any definite result can be reached. 



(0) Distichum x decipiens, i.e. (F) x (G). 



The 1:2:1 ratio has been well established ; hence (F) and (G) are 

 allelomorphic characters. 



{(,) Distichum x distichum {H. inerme). 



Only by complete ^3's (to be grown in 1920) can this cross be 

 properly studied. 



(«) Decipiens x distichum (H. inerme). 

 No observations are available. 



The above categories of crossing results may be summarised thus : 



