280 Mr Biffen, Wheat Breeding. 



where a single, pair are taken into account. Where two pairs are 

 counted out the combinations agree with those predictable from a 

 consideration of Mendel's laws. Thus a velvet-chaffed, white wheat 

 was crossed with a smooth-chaffed, red wheat. The hybrid was 

 velvet-chaffed and red-grained, and its progeny consisted of 45 

 velvet-chaffed red-grained, 15 velvet-chaffed white-grained, 16 

 smooth-chaffed red-grained, and 5 smooth-chaffed white-grained 

 plants out of a total of 81 — i.e. in the proportion of 9 : 3 : 3 : 1. 

 As far as I have worked out the results for three and more 

 pairs of characters, they also conform with the ratios deduced 

 theoretically. 



It may be taken as proved then, that, for the majority of 

 characteristics at all events, wheats follow Mendel's laws. At the 

 same time it is worthy of note that in some cases the hybrid does 

 not show certain of the dominant characters as clearly as the 

 parent, whilst in other cases the characters seem to be intensified. 

 Generally speaking it is the most variable characters of the parents 

 which give these results. 



A typical case is afforded by the grey colouring of the chaff of 

 Rivet wheat, which varies considerably in intensity, not only among 

 individual plants but among the ears of the same plant. This 

 wheat has been crossed with a number of white-chaffed and red- 

 chaffed wheats, and in every case the hybrids obtained have been 

 variable in colour, none being as dark as the original Rivet wheat, 

 and none as pale as the other parent. In the following generation 

 the extent of the variation is extraordinary, the colour ranging 

 from almost black to isabelline white, the intermediate colours 

 being the most numerous. 



Apparently a similar phenomenon has occurred among Tscher- 

 mak's hybrids between red and white wheats, and he has been 

 able to show that two intermediates are found to one of red and 

 one of white. It may. be that the same type of splitting occurs 

 among the grey and white hybrids, but the colour gradation is so 

 subtle that I have not been able to decide into which classes the 

 plants should be placed, especially as in some cases each ear would 

 nave required a separate class. 



The characters lax and dense ears give the same sort of result. 

 In the hybrid the ear is a little laxer than the lax parent (pro- 

 bably a correlation with increased height), and in the following 

 generation a small number of very lax and very dense ears occur, 

 the majority lying between these extremes. 



Velvet and smooth chaff again offer a difficulty. Where Rough 

 chaff wheat is the velvet parent, the velvet character is transmitted 

 in full intensity to the hybrid and the splitting is pure. Where 

 Rivet wheat is the velvet parent though the "felting" of the 

 hybrid is variable and in its progeny still more variable — in fact 



