GENERAL OBSERVATIONS AND CONCLUSIONS. 451 



species marked E were cultivated before the discoveries 

 of Columbus, perhaps for more than two thousand years. 

 Many other species marked (?) in the table date probably 

 from an ancient epoch, but as they chiefly exist in 

 countries without a literature and without archaeological 

 records we do not know their history. It is useless to 

 insist upon such doubtful categories ; on the other hand, 

 the plants which we know to have been first cultivated 

 in the old world less than two thousand years ago, and in 

 America since its discovery, may be compared with plants 

 of ancient cultivation. 



These species of modern cultivation number sixty-one 

 in the old world, marked C, and six in America, marked 

 F ; sixty-seven in all. 



Classed according to their duration, they number 

 thirty-seven per cent, annuals, seven to eight per cent, 

 biennials, thirty-three per cent, herbaceous perennials, 

 and twenty-two to twenty-three per cent, woody species. 



The proportion of annuals or biennials is also here 

 larger than in the whole number of plants, but it is not 

 so large as among species of very ancient cultivation. 

 The proportions of perennials and woody species are less 

 than in the whole vegetable kingdom, but they are higher 

 than among the species A, of very ancient cultivation. 



The plants cultivated for less than two thousand 

 years are chiefly artificial fodders, which the ancients 

 scarcely knew ; then bulbs, vegetables, medicinal plants 

 (Cinchonas) ; plants with edible fruits, or nutritious seeds 

 (buckwheats) or aromatic seeds (cofiee). 



Men have not discovered and cultivated within the last 

 two thousand years a single species which can rival maize, 

 rice, the sweet potato, the potato, the bread-fruit, the date 

 cereals, millets, sorghums, the banana, soy. These date 

 from three, four, or five thousand years, perhaps even in 

 some cases six thousand years. The species first culti- 

 vated during the Grseco-Roman civilization and later 

 nearly all answer to more varied or more refined needs. 

 A great dispersion of the ancient species from one country 

 to another took place, and at the same time a selection of 

 the best varieties developed in each species. The introduc- 



