496 POPULAR SCIENCE MONTHLY. 



now generally agreed that the tribes, languages and arts of the Ameri- 

 can Indians are of truly indigenous development, while it is held, on 

 the other hand, that the Polynesians migrated eastward from Asia, but 

 without reaching the shores of America. That these two suppositions 

 can not both be true is apparent as soon as it is known that there has 

 been a transfer of numerous cultivated plants between Polynesia and 

 America, and other agricultural facts enable us to judge between the 

 inconsistent theories. Since it is reasonable to suppose that the food 

 plants which the Polynesians shared with the tropical peoples of both 

 continents were carried by them across the Pacific, it is also reasonable 

 to seek the origin of these widely distributed species on the continent 

 which gives evidence of the oldest and most extensive agricultural 

 activity, and to the question in this form there can be but one answer. 

 The agriculture of the old world tropics is adequately explainable by 

 the supposition that it was brought by the Polynesians, since the root- 

 crops of the Polynesians were also staples of the old world tropics. 

 This proposition would not apply to America, where, in addition to 

 the sweet potato, yams, yam-bean (Pachyrhizus) and taro, which crossed 

 the Pacific, the aborigines also domesticated a long series of root- 

 crops — Manihot (cassava), Maranta (arrowroot), Calathea (lleren), 

 Solarium (Irish potato), Xanthosoma (several species), Oxalis (Oca), 

 Carina, Tropceolum, Ullucus, Arracacia, Sechium and Helianthus (arti- 

 choke), all of considerable local importance. 



The simplest of cultural methods, propagation from cuttings, was 

 applied to all these root-crops* and has been in use for so long a period 

 that several of them have become seedless. With equal uniformity the 

 distinctively old world root-crops are grown from seed. American 

 root-crops belong to at least twelve natural families, and the only 

 important old world addition to the series is the mustard family, a 

 distinctly temperate group, the cultivated members of which have not 

 been greatly modified in domestication, and are still known in the 

 wild state. 



This apparent superfluity of American root-crops is explainable by 

 the fact that different plants were independently domesticated in differ- 

 ent localities, which means also that conditions favorable to the develop- 

 ment of agriculture were very general among the natives of America. 

 That most of these plants are not known in the wild state testifies also 



* Sechium is perhaps an exception, but the more varied and localized names 

 of the root are an indication that this plant was first domesticated as a root- 

 crop. It may also be noted that Sechium is peculiarly adapted for teaching the 

 art of planting seeds, since the fruit does not decay, but remains alive and 

 edible long after the contained seed has germinated and sent forth a new vine 

 with its leaves and roots. ('See 'The Chayote: A Tropical Vegetable,' Bulle- 

 tin No. 28, Div. of Botany, U. S. Dept. of Agriculture.) 



