A sixth kind, the common T. spelta, was not introduced into Switzerland until the Bronze age. Of barley, besides the short-eared and small-grained kind, two others were cultivated, one of which was very scarce, and resembled our present common H. distichum. During the Bronze age rye and oats were introduced; the oat- grains being somewhat smaller than those produced by our existing varieties. The poppy was largely cultivated during the Stone period, probably for its oil; but the variety which then existed is not now known. A peculiar pea with small seeds lasted from the Stone to the Bronze age, and then became extinct; whilst a peculiar bean, likewise having small seeds, came in at the Bronze period and lasted to the time of the Romans. These details sound like the descriptions given by palaeontologists of the first appearance, the increasing rarity, and final extinction or modification of fossil species, embedded in the successive stages of a geological formation.
Finally, every one must judge for himself whether it is more probable that the several forms of wheat, barley, rye, and oats are descended from between ten and fifteen species, most of which are now either unknown or extinct, or whether they are descended from between four and eight species, which may have either closely resembled our present cultivated forms, or have been so widely different as to escape identification. In this latter case we must conclude that man cultivated the cereals at an enormously remote period, and that he formerly practised some degree of selection, which in itself is not improbable. We may, perhaps, further believe that, when wheat was first cultivated the ears and grains increased quickly in size, in the same manner as the roots of the wild carrot and parsnip are known to increase quickly in bulk under cultivation.
[MAIZE OR INDIAN CORN: Zea mays.
Botanists are nearly unanimous that all the cultivated kinds belong to the same species. It is undoubtedly (9/50. See Alph. De Candolle's long discussion in his 'Geograph. Bot.' page 942. With respect to New England see Silliman's 'American Journal' volume 44 page 99.) of American origin, and was grown by the aborigines throughout the continent from New England to Chili. Its cultivation must have been extremely ancient, for Tschudi (9/51. 'Travels in Peru' English translation page 177.) describes two kinds, now extinct or not known in Peru, which were taken from tombs apparently prior to the dynasty of the Incas. 'But there is even stronger evidence of antiquity, for I found on the coast of Peru (9/52. 'Geolog. Observ. on S. America' 1846 page 49.) heads of maize, together with eighteen species of recent sea-shell, embedded in a beach which had been upraised at least 85 feet above the level of the sea. In accordance with this ancient cultivation, numerous American varieties have arisen. The aboriginal form has not as yet been discovered in the wild state. A peculiar kind (9/53. This maize is figured in Bonafous' magnificent work, 'Hist. Nat. du Mais' 1836 P1. v. bis, and in the 'Journal of Hort. Soc.' volume 1 1846 page 115 where an account is given of the result of sowing the seed. A young Guarany Indian, on seeing this kind of maize, told Auguste St. Hilaire (see De Candolle 'Geograph. Bot.' page 951) that it grew wild in the humid forests of his native land. Mr. Teschemacher in 'Proc. Boston Soc. Hist.' October 19, 1842 gives an account of sowing the seed.), in which the grains, instead of being naked, are concealed by husks as much as eleven lines in length, has been stated, but on insufficient evidence, to grow wild in Brazil. It is almost certain that the aboriginal form would have had its grains thus protected (9/54. Moquin-Tandon 'Elements de Teratologie' 1841 page 126.); but the seeds of the Brazilian variety produce, as I hear from Professor Asa Gray, and as is stated in two published accounts, either common or husked maize; and it is not credible that a wild species, when first cultivated, should vary so quickly and in so great a degree.