132 Ghime Length in Triticuni Polonicum 



already made with the same strains of Rivet and of Polish wheats as 

 used by Biffen. The first generation was grown at Pergainino, in 1913, 

 and was notable from the start as being decidedly tinged. The second 

 generation was divided and grown, in 1914, in three different places, 

 viz. in the north, centre and south of the wheat producing area of the 

 Argentine Republic. In the north, all the individuals were colourless, 

 as in England. In the centre, at the latitude of Buenos Aires, some of 

 the short glumed individuals were tinged. In the south, in the Pampa, 

 the coloured ones were fairly clearly defined and could be classified, giving 

 the following proportions : 



Rivet X Polish F.,. Guatrache, Pampa. 



Long and Intermediate 



glume length Short glume length 



72 30 



Coloured White Coloured White 



72 7 23 



Three doubtful shorts grown in 1915, to test, bred true to short 

 glume, but not to colour, and gave a total of 7 white to 13 coloured. 

 The proportion is peculiar but it is always difficult to distinguish the 

 homozygous coloured individuals from the heterozygous tinged one.s. 



Polish x Rivet F«. (Reciprocal of the other cross.) 



Long and Intermediate 



glume length Short glume knigth 



25 9 



Coloured White Coloured White 



25 4 .5 



It will be observed that here again the coloured individuals are only 

 found among the short glumed categor}'. The coloured segregates of 

 these crosses are never quite so deeply coloured as Pedigree Rivet wheat 

 itself and grade almost imperceptibly from coloured to tinged and tinged 

 to colourless. 



The interest of the experiment, however, lies in the fact that, whereas 

 in England the colour disappears and does not return in any subsequent 

 generation, the result of growing i^^s, obtained in identically the same 

 way, in the Argentine, is to prove that at any rate the colour is there 

 and, given suitable climatic conditions, will show itself. Rivet wheat, 

 grown for comparison, had the same peculiar mouse-grey colour as in 

 England and was no darker in this climate. 



