Breeding of Cereals 79 
Few of the varieties of wheat show conspicuous differences, 
although their number is great. If we compare the differentiating 
characters of the smaller types of cereals with those of ordinary 
wild species, even within the same genus or family, they are obviously 
much less marked. All these small characters, however, are strictly 
inherited, and this fact makes it very probable that the less obvious 
constituents of the mixtures in ordinary fields must be constant and 
pure as long as they do not intercross. Natural crossing is in most 
cereals a phenomenon of rare occurrence, common enough to admit of 
the production of all possible hybrid combinations, but requiring the 
lapse of a long series of years to reach its full effect. 
Darwin laid great stress on this high amount of variability in the 
plants of the same variety, and illustrated it by the experience of 
Colonel Le Couteur! on his farm on the isle of Jersey, who cultivated 
upwards of 150 varieties of wheat, which he claimed were as pure as 
those of any other agriculturalist. But Professor La Gasca of Madrid, 
who visited him, drew attention to aberrant ears, and pointed out, 
that some of them might be better yielders than the majority 
of plants in the crop, whilst others might be poor types. Thence 
he concluded that the isolation of the better ones might be a 
means of increasing his crops. Le Couteur seems to have con- 
sidered the constancy of such smaller types after isolation as 
absolutely probable, since he did not even discuss the possibility 
of their being variable or of their yielding a changeable or mixed 
progeny. This curious fact proves that he considered the types, dis- 
covered in his fields by La Gasca to be of the same kind as his other 
varieties, which until that time he had relied upon as being pure and 
uniform. Thus we see, that for him, the variability of cereals was 
what we now call polymorphy. He looked through his fields for useful 
aberrations, and collected twenty-three new types of wheat. He was, 
moreover, clear about one point, which, on being rediscovered after 
half a century, has become the starting-point for the new Swedish 
principle of selecting agricultural plants. It was the principle of 
single-ear sowing, instead of mixing the grains of all the selected 
ears together. By sowing each ear on a separate plot he intended 
not only to multiply them, but also to compare their value. This 
comparison ultimately led him to the choice of some few valuable 
sorts, one of which, the “Bellevue de Talavera,” still holds its place 
among the prominent sorts of wheat cultivated in France. This 
variety seems to be really a uniform type, a quality very useful under 
favourable conditions of cultivation, but which seems to have de- 
stroyed its capacity for further improvement by selection. 
The principle of single-ear sowing, with a view to obtain pure and 
1 On the Varieties, Properties, and Classification of Wheat, Jersey, 1837. 
