1905.] 



Cross-fertilisation of Wheat. 



475 



dinctly favourable. Strength is sometimes to be found in grain 

 which has a soft, opaque endosperm, but more commonly where 

 the strength of wheat is to be estimated by the way it behaves 

 when used by itself, and not in combination with other sorts, it 

 is indicated, especially in cases where the natural moisture is 

 approximately alike, by the possession of a hard translucent 

 endosperm, and weakness by a soft, opaque endosperm. Mr. R. 

 H. Biffen, the Botanist of the Agricultural Department at 

 Cambridge University, crossed Polish (the Durum triticum 

 polomcum, not the soft wheat which was sold in England as- 

 Polish wheat many years ago), on to Rivet to see the effect on 

 the character of the endosperm. The grain produced as the 

 result of the cross was hard. This was planted, and the grain 

 of the first generation (F 1) was all hard, which looked as if the 

 characteristics were Mendelian, and the hard translucent endo- 

 sperm of the Polish the dominant. In the second generation 

 of the plants (F 2), he obtained some hard, some soft, but it is^ 

 not certain as yet whether they were in the Mendelian ratio of 

 three to one. Tested by the Kjeldahl method, the Polish parent 

 had 2*4 per cent, total nitrogen, the Rivet r8 per cent. The 

 hybrids had a varying range from 2*45 per cent, to 172 per cent. 

 In another case he crossed Red Fife on to White Rough Chaff, 

 the former a relatively brittle round-berried wheat, the latter a 

 long-berried wheat, frequently with a soft, fluffy endosperm- 

 Two samples were sent to Mr. Humphries, who, without 

 hesitation, declared one to be Fife and the other Rough 

 Chaff ; whereas, in fact, one was a dominant from the F 2 

 generation of the cross Fife and Rough Chaff, the other the 

 fixed recessive form from the same generation. These and 

 several other cases enable it to be said definitely that whether 

 strength and weakness are a Mendelian " duality " or not, yet as- 

 the result of many crosses many varieties have been obtained 

 possessing in an apparently pure form the endosperm characters 

 of one or the other of the two parents, not a blend of both ; 

 and many hybrids are being propagated which it is believed do 

 possess in combination the strength of the strong parents and 

 the high yielding characteristics of the weaker parents, in the 

 belief that they will breed true in the possession of that desired 

 combination. The first novelty to materialise is a Rough Chaff 



