Africa, maize, the potato, the yam, and the manioc in America, were evidently easily and soon cultivated under the inducements offered by their obvious good qualities and favorable climatical conditions. Centers were thus formed, and hence the most useful species were diffused. In the north of Asia, Europe, and America, the temperature is unfavorable, and the indigenous plants are sparsely productive; but, as the resources of hunting and fishing are available, the introduction of agriculture could be delayed, and the people could do without the valuable species of the South without suffering much. It was otherwise in Australia, Patagonia, and Southern Africa. The plants of the temperate regions of our hemisphere could not reach these countries on account of the distance, and those of the intertropical zone were excluded from them by the excessive drought or the absence of high temperatures. At the same time the native species were miserable in quality. It was not want of intelligence or of security alone that prevented the inhabitants from cultivating them. Their nature also discouraged the effort to such an extent that the Europeans, during the hundred years they have been in these countries, have only attempted the cultivation of a single species, the tetragonia, an inferior green herb. I do not forget that Sir Joseph Hooker has enumerated more than a hundred Australian species that might be used in some way; but, in fact, they have not been cultivated, and they are not cultivated, with all the improved processes which the English colonists possess. This demonstrates the principle I have just announced, that the quality of the species has an influence on the selection, and that there must be real qualities in a wild plant to induce an effort to cultivate it.
Notwithstanding the obscurity that surrounds the beginnings of agriculture in different regions, it is settled that the dates vary exceedingly. One of the earliest examples of cultivated plants is drawn from Egypt, in the shape of a design representing figs in one of the pyramids of Gizeh. The date of the construction of the monument is uncertain; authors vary in assigning it to from fifteen hundred to four thousand two hundred years before the Christian era. If we assign it to two thousand years before Christ, we would have an antiquity of four thousand years for the fig. Now, the pyramids can have been constructed only by a numerous people, organized and civilized to a certain degree, who must consequently have had an established agriculture, going back several centuries, at least, for its origin. In China, twenty-seven hundred years before Christ, the Emperor Chennung introduced a ceremony in which, every year, five species of useful plants were sown—viz., rice, soja, wheat, and two kinds of millet. These plants must have been cultivated for some length of time in some places to have attracted the attention of the emperor at this period.
Agriculture seems, then, to have been as ancient in China as in Egypt.
