ON RECENT DEVELOPMENTS IN AGRICULTURAL SCIENCE. 279 
clusive, some idea of the factors determining this quality has been 
reached from practical baking tests combined with measurements of the 
gluten and nitrogen content of the flour. In the first place manuring 
proves a very small factor; the composition of the grain of wheat is 
extraordinarily stable and the plant reacts to diversities in nutrition by pro- 
ducing more or less grain rather than by altering its composition. Even 
under the exceptionally pronounced variations in the manurial conditions 
of the Rothamsted plots, the composition of the grain fluctuates more 
with changing seasons than with changed manuring. Within the limits 
of healthy growth and ripening the date of sowing the wheat has no 
effect upon the quality of the grain; the same wheat sown at monthly 
intervals from October to March gave practically identical quality in the 
grain, and a number of comparisons between autumn and spring sowing 
led to no definite conclusion. Soil has also a comparatively small effect, 
though, of course, different soils, by inducing differences in the supply of 
water to the plants and in the temperature, practically result in differ- 
ences of climate. The effect of climate is large, whether tested by grow- 
ing the same variety in different countries or by inducing artificial 
variations in the climate of wheats grown under experimental conditions. 
But while the climatic factor proves to be large it is less than was antici- 
pated : an English soft wheat, for example, grown on the Hungarian 
plain for two seasons has not altered greatly in character nor taken on’ 
the characteristic appearances of the wheat of the district. A specially 
strong wheat from the Canadian North-West, after some considerable 
fall of strength in the first English crop, has fallen no further after three 
successive crops, and still retains all the characters of an exceptionally 
strong wheat, although the yield remains poor from an English stand- 
point. Other varieties have rapidly and entirely lost their strength when 
changed to English conditions from America, or Hungary, or Russia ; 
many, however, while showing the effect of climate yet stand apart from 
the typical English wheats and show no tendency to ‘ acclimatise’ in the 
sense of acquiring the character of the local varieties. In the whole work 
the thing which stands up most prominently is the fundamental import- 
ance of the ‘ variety’; each race, each botanical unit as it were, possesses’ 
an individuality and yields grain of a characteristic composition ; and 
though climate, soil, season, manuring, are factors producing variation 
in the composition, they are all small compared with the intrinsic nature 
of the variety itself. Similar conclusions follow from the work of Wood 
and his colleagues upon the composition of mangels, and of Collins on 
the composition of swedes. The proportion of dry matter and sugar in 
the root, while varying markedly in the individual roots, possesses a 
typical value for each race ; and though season, locality, and to sume 
extent manuring affect the composition, the changes thus induced are 
not great. 
Starting, then, from this point, that variety or race is the chief factor 
in the composition of a given plant, and that, once the variety is fixed, 
the other factors, which are more or less under control, such as manuring, 
soil, and climate, have but minor effects upon the quality, the road to 
the improvement of the quality of our farm crops lies in the creation of 
new varieties by breeding. An improved variety is all clear gain to the 
farmer ; climate, season, and to a large extent soil are outside his con- 
trol ; while better manuring and cultivation, however much their cost 
may be lessened by increased skill, yet involve expenditure and become 
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