762 DISCUSSION ON WHEAT: 
The solution of such a problem requires a knowledge of the inheritance 
of characteristics peculiarly difficult to deal with. A casual inspection of 
a plant is sufficient to determine whether it is bearded, velvet-chaffed, red, 
&e., but strength, yield, and stiffness of straw cannot be determined so 
steadily. In fact, the single plants the breeder now deals with—instead of 
the mass, as before—give him no information of value as to capacity to 
afford a heavy yield of grain or stiff straw. Such features can only be 
determined by actual and, in view of their number, costly field trials. In 
the characteristic ‘strength’ the problem is not quite so complex, as by 
choosing varieties showing extremes of strength and weakness as parents 
it is possible to differentiate these with sufficient accuracy for technical 
purposes when segregation has occurred. 
The mode of inheritance of strength was first determined by crossing 
Red Fife with Rough Chaff, the former parent having strong grain of a 
red colour, the latter weak grain of a white colour. Like most weak wheats; 
the grain of Rough Chaff is soft and of a texture well described as floury, 
whilst that of Fife is hard and translucent. The texture of the grain has 
proved singularly constant under our experimental conditions and a good 
index as to the baking quality of flour from the grain. The generation 
raised from the plant arising from this combination of the parents, the F., 
of the Mendelians, showed obvious segregation into strong and weak wheats, 
these characteristics being entirely independent of such others as the velvet 
nature of the chaff, the grain colour, &c. Thus in this generation the 
following obvious types occurred :— 
Strong, velvet-chaffed, red. Weak, velvet-chaffed, red. 
Strong, velvet-chaffed, white. Weak, velvet-chaffed, white. 
Strong, smooth-chaffed, red. Weak, smooth-chaffed, red. 
Strong, smooth-chaffed, white. Weak, smooth-chaffed, white. 
On determining the proportion of strong-grained to weak-grained indi- 
viduals there were found to be three of the former present to every one of 
the latter, the distribution of the two forms being uniform in the eight 
types mentioned above. Strength in this case, then, proved to be simply 
dominant to lack of strength. In the following season a number of pure 
strong types were isolated and grown on again the following year, in order 
to obtain sufficient grain for tests in the bakehouse. The results of these 
tests confirmed the view arrived at from an examination of the grain of 
the F., generation, and left no doubt that the strength of these hybrids was 
of the same order as that of the parent Red Fife. ; 
In many other cases the simple Mendelian ratios are not so readily 
ascertainable, owing to the varieties chosen as the weak parents producing 
semi-translucent grain. Under such conditions the well-known chewing test 
of the wheat buyer is generally sufficient to show that segregation has 
occurred and to enable the breeder to pick out the strong types for further 
tests. 
Whilst these investigations were in progress some of the late W. Farrev’s 
Fife crosses were being obtained in sufficient bulk for baking tests. These 
also proved to be ‘ fully as strong as Fife.’ Thus the facts at our disposal 
seem to warrant the statement that strength is a unit character. Com- 
plications may and probably do exist, much as they do with the colour 
characteristics of wheat, but of this nothing is known at present; so far 
the only exception taken to this view has been based on cases in which the 
actual baking strength of the parent plants is unknown. 
The strong wheats of the world are at present cultivated almost exclu- 
sively in countries in which the yield per acre is small; where large yields 
are the rule the weaker types only are in general cultivation. It has con- 
sequently been assumed that strength and lowness of yield are correlated 
