272 ORIGIN AND DISTRIBUTION OF THE COCOA PALM. 
interest because it was intended to explain the probability that the 
yam was not in use in Sanserit. times, or at least had no distinctive 
name, In China, as in the Malay region, Polynesia, and America, 
yams appear to have been among the earliest, as they are still the most 
important, of cultivated root crops. The Chinese yam (Dioscorea 
batutas) never penetrated India, has never been reported in the wild 
condition, and was probably not a native of the Asiatic continent. 
Several other species cultivated in India and neighboring regions are 
also not known in the wild state, and presumably came from farther 
east. The probability that Déoscorea alata, at least, was carried west- 
ward by the primitive race which transported the cocoanut is very 
great, and is supported by the fact that the yam bean (Pachyrhizus), a 
leguminous plant with a large yam-like root, and of even more highly 
probable American origin, was introduced in prehistoric times and is 
still sparingly cultivated in India. In Polynesia the use of Pachyrhizus 
in religious ceremonies seems to indicate former cultivation, but what is 
still more interesting, the Polynesians, like the aborigines of America, 
had knowledge anticipating the modern discovery of the fertilizing 
ralue of leguminous crops, and encouraged the growth of Pachyrhizus 
in their fallow clearings in order to render the land more quickly able 
to yield good crops of yams.' 
The sweet potato furnishes another instance of the trans-Pacitic 
distribution of a useful plant in prehistoric times, though it may have 
come into use later or traveled less rapidly than the cocoanut. In the 
equatorial belt the sweet potato was doubtless, as it still is,a much less 
important crop than the yam, but among the subtropical Hawatians 
and Maoris it is believed to have been the principal food plant. As 
with the cocoanut, the sweet potato was designated by cognate names 
throughout the entire Pacific region, and, moreover, it affords a 
philological argument wanting with the cocoanut, since the Polynesian 
names ward, kumara, and gunara, ave apparently represented on the 
continent of America by the word ear, in the language of the Indians 
of EKeuador. The Mexican name ‘‘camote,” supposed to have been 
transferred to the Philippines in Spanish times, may also be derived 
from the same linguistic root. Like the banana, the sweet potato has 
become seedless through long cultivation and propagation exclusively 
from cuttings. The theory of distribution by ocean currents has here 
no standing; but the’ botanical evidence of American origin is not 
nearly as strong as in the case of the cocoanut, since many other 
species of the same and related genera are very widely spread through 
1Engler’s Bot. Jahrb., vol. 25, p. 640 (1898). 
2 Tn addition to this name the people of one of the Viti Islands have a term which 
means ‘‘foreign yam,’ a possible indication of an arrival subsequent to that of the 
yam. . 
