A. St Clair Caporn 269 



It should be emphasized that whenever an insufficient number of 

 plants forjudging was present in an F^ row of which the parental colour 

 was doubtful, or roguing was suspected, these cases were not included 

 in the count; so that the 27 flusheds, 8 streakeds, and 123 non- 

 coloureds contain no individuals about which any uncertainty exists. 

 Furthermore, although no particular note was made regarding the 

 matter, very probably the grains frmn which these 180 or so Fo plants 

 were derived all came off a single F^ plant. For, in spite of poor 

 tillering power, plants of later generations with a fair amount of room, 

 such as those at the end of rows, were observed with five or six well 

 filled ears ; whereas among the F^ individuals the encouragement to 

 tiller is considerably greater, since they are always purposely well 

 spaced. 



Apparently, then, one, and only one, heterozygous combination gave 

 rise to the F.^ generation. This conclusion is supported by the sim- 

 plicity of the ratio : it is too even to be a fortuitous mixture of different 

 F« segregation systems. For 27 : 8 : 123 is, considering the not very 

 large number of plants involved, a reasonably close approximation to 

 3:1:12, the actual expectation being 30 : 10 : 118. 



In view of the full purple colour of the F^ grains, the minor pro- 

 portion of flushed forms in the F<> generation is very striking. No less 

 so is the behaviour of the 123 non-coloureds, of which 



111 threw non-coloureds only, and 

 12 „ „ „ -I- streakeds. 

 [In the 12 non-coloureds absence of colour was apparently a dominant, 

 as the streakeds made up the smaller part of the offspring.] 



Now if the ratio 3 : 1 : 12 be expressed in the form 48 : 16 : 192, 

 the third term can be conveniently split up on a 1.5 : 1 basis so that 

 the whole may be restated thus, 



48 : 16 : (180-1-12). 



On applying this to the F.2 results the comparison with expectation 

 reads as follows : 



Observed. 27 flusheds : 8 streakeds : (111 + 12) non-coloureds. 

 Expected. 30 „ : 10 „ : (111 + 7) 



While, therefore, the probability cannot be pressed to the verge of 

 certainty, there is still ground for believing that the two kinds of non- 

 coloureds in the F^ generation were to each other as 1-5 to 1. 



To speculate on the Mendelism of these figures at this stage were 



