Improvement of the Plants of the Farm. 
87 
No one doubts that the numerous varieties of maize have 
descended from a single source. Yet this plant, once confined to 
one spot, now ranges through greater extremes of climate perhaps 
than any other grain-crop. Dr. Vasey, Botanist to the Depart- 
ment of Agriculture, Washington, has favoured me with the 
following reply to an inquiry as to the localities of the varieties 
of maize. 
" Another enquiry is as follows : — ' Are these different sorts of maize 
adapted to different districts, and can a definite line be drawn between the 
districts which produce the large, flat, rough seed, and those which produce 
the smooth, round, yellow seeds?' To this it may be answered that there 
are several varieties of each of the two classes of corn or maize referred to in 
the question, and that in general the large, rough-seeded varieties are best 
adapted to Southern districts, and the smaller, smooth round varieties to 
Northern districts ; yet no delJhite line can be drawn farther, ])erhaps, than 
to say that the large varieties cultivated in the extreme South will not succeed 
in the extreme Xorth, for the want of a sufiBciently long season to mature the 
grain." 
The varieties of maize and their differences may be studied 
in the first volume of Mr. Darwin's 'Animals and Plants under 
Domestication,' and in the works which he refers to ; or a more 
popular work mav be consulted — the ' Grain Manual ' — pub- 
lished by Messrs. Hiram, Sibley and Co., the great seedsmen of 
Rochester and Chicago. In southern districts maize requires 
six or seven months as the period of its growth, while the dwarf 
kind, which are habituated to the short summer of the north, 
require only from three to four months. The height of the 
plant is 15 or 18 feet in some climates, and 16 or 18 inches in 
the case of dwarf varieties in northern countries. The size 
of the ear and of its seeds varies in like manner. There are 
kinds which ripen their seeds six weeks earlier than other kinds. 
Maize from the furthest south will hardly ripen a seed in New 
England, and the maize of New England will scarcely ripen in 
Canada. But with care and culture the southern kinds, after 
a few years, ripen their seeds perfectly in their northern homes, 
furnishing, as Mr. Darwin observes, " an analogous case to the 
conversion of summer into winter wheat, and conversely." 
The principle of selection has been applied to rice as well as 
maize, and among various other cases in point, I may quote 
that of the Chinese Emperor Khang-hi, an improver several 
thousand years ago, who selected and sowed in his garden, 
and afterwards " introduced " to China, the only kind of rice 
which will grow north of the Great Wall. 
It is useful to know that the several varieties of cereals, with 
their infinite differences of character, are not produced, as might 
be imagined, by the influence of diverse soils and climates, but 
by the prodigality of nature. It is doubtful whether climate, 
