ORIGIN OF DOMESTIC PLANTS. 59 
of domesticated plants, and scientific journals have described 
the experiments by which the identity of particular wild and 
cultivated vegetables has been thought to be established. It is 
confidently aftirmed that maize and the potato—which we must 
suppose to have been first cultivated at a much later period 
than the breadstuffs and most other esculent vegetables of 
Europe and the East—are found wild and self-propagating in 
Spanish America, though in forms not recognizable by the 
common observer as identical with the familiar corn and tuber 
of modern agriculture. It was lately asserted, upon what 
seemed very strong evidence, that the Zylops ovata, a plant 
growing wild in Southern France, had been actually converted 
into common wheat ; but, upon a repetition of the experiments, 
later observers have declared that the apparent change was 
only a case of temporary hybridation or fecundation by the 
pollen of true wheat, and that the grass alleged to be trans- 
formed into wheat could not be perpetuated as such from its 
own seed. 
The very great modifications which cultivated plants are con- 
stantly undergoing under our eyes, and the numerous varieties 
and races which spring up among them, certainly countenance 
the doctrine, that every domesticated vegetable, however de- 
pendent upon human care for growth and propagation in its 
present form, may have been really derived, by a long succes- 
sion of changes, from some wild plant not now perhaps much 
resembling it.* But it is, in every case, a question of evidence. 
* What is the possible limit of such changes, we do not know, but they may 
doubtless be carried vastly beyond what experience has yet shown to be practi- 
eable. Civilized man has experimented little on wild plants, and especially on 
forest trees. He has indeed improved the fruit, and developed new varieties, 
of the chestnut, by cultivation, and it is observed that our American forest-tree 
nuts and berries, such as the butternut and the wild mulberry, become larger 
and better flavored in a single generation by planting and training. (BRYANT, 
Forest Trees, 1871, pp. 99, 115.) Why should not the industry and ingenu- 
ity which have wrought such wonders in our horticulture produce analo- 
gous results when applied to the cultivation and amelioration of larger vege- 
tables? Might not, for instance, the ivory nut, the fruit of the Phytcephas 
