308 Mr Biff en, Experiments on the Hybridisation of Barleys. 



the laxness or denseness of the ear. In the following generation 

 three forms of ear occur, the six-row, two-row, and the decipiens, 

 in the proportion of 1 : 2 : 1. The reciprocal crosses give precisely 

 the same results. Only one F 3 of this combination of characters 

 has yet been grown, and that unfortunately a small one. It serves, 

 however, to show that the forms with the male laterals produced 

 in the F 2 are true heterozygotes, since they give rise to individuals 

 with hermaphrodite or with sexless laterals as well as the form with 

 staminate lateral florets only. These latter are indistinguishable 

 from the two-row barleys in general cultivation as far as external 

 appearances go. Summarizing this part of the story, then, we may 

 say that the result of crossing varieties with sexless and with her- 

 maphrodite laterals is to suppress the production of the female 

 portion, so giving a unisexual male heterozygote. 



It remains now to consider the results of crossing together 

 varieties with male and hermaphrodite lateral florets. My first 

 experiments in this direction led me to conclude that the hetero- 

 zygote in such cases was a true two-rowed individual, and that its 

 progeny consisted of three of the former to one of the latter type. 

 More recently I have found cases in which the heterozygote bore a 

 few undoubtedly fertile florets in the lateral rows, and such occur 

 amongst its offspring in the following generation. If such are to 

 be included in the group with male laterals and looked upon as 

 abnormalities, which as a matter of fact occur from time to time 

 in the two-rowed varieties, then the segregation is normal, for 

 there are three two-rowed individuals to each two-rowed. It is 

 more probable though that we again have to deal with an inter- 

 mediate heterozygote in which the formation of small but normally 

 fertile florets is the rule, but, as there are complications occurring, 

 very possibly owing to differences of nutrition, the further descrip- 

 tion of this case must be deferred until the individuals from the 

 F2, assumed to be heterozygotes, have been tested in the following 

 generation. 



