92 
Improvement of the Plants of the Fann. 
wonderful feats performed by breeders in the department of 
horticulture. He writes — 
" Grardeners, as you know, cross very largely all sorts of things, but they 
have to do it on a very large scale and to exercise undaunted patience, because 
they draw so many blanks and so lew prizes. But it is a curious fact that 
while the first generation is often a mass ot worthless mongrels, some of those 
mongrels, if grown on, eventually develop into something good." 
We have seen that Mr. ShirrefF's crossed varieties of wheat 
scarcely answered his expectations ; but he was a breeder for 
a period so short, that even failure under such circumstances 
need not deter others, since all the triumphs of plant-improve- 
ment have been due to the crossing of varieties and to selection. 
It was by these processes, as we have seen, that maize has been 
spread over such extended districts ; and varieties of wheat of 
improved sorts, each suited to its district, will reward those who 
patiently attend to this branch of cultivation. The principles 
of plant-improvement, however, must be mastered by those who 
would practice the art. 
. A selector of wheat has maintained, correctly enough no doubt, 
that every ear contains one grain more productive than the rest ; 
but in carrying out the principle of selection he sowed his best 
seeds at wide intervals. This kind of seeding means high 
feeding, and produces large coarse grain and stout weak straw. 
It induces, therefore, constitutional defects, with probably a pre- 
disposition to blight and mildew, and the other diseases to which 
enfeebled plants are specially liable. In well-farmed fields the 
best seeds select themselves, since their produce is greater than 
that of others, and therefore every year a larger proportion of the 
most productive seed must be sown. It is sown, too, on clean 
land, sufficiently but not too heavily manured, under conditions 
most favourable to the health of the plant. No doubt the art of 
plant-improvement consists in the selection of good qualities and 
of profitable modifications ; but when the improver introduces 
another principle, that of high feeding by thin sowing, he alters 
the plant by a totally different method Irom that employed by 
the selector. As a general rule, the improver should aim to 
produce varieties yielding grain of superior quality. A coarse 
and vigorous variety may be excellent for poor soils, but when 
the thin seeding is carried so far as to render the grain unusually 
large and light, there is then danger of disaster through im- 
paired vitality and constitutional vigour. A habit of excessive 
tillering is induced by early and thin seeding, and wheat which 
had acquired that habit has been known to continue tillering in 
the summer — having been sown in the spring — and to be still 
spreading over the ground a grassy mat of herbage, when 
other varieties, sown at the same time, were in ear. 
