Fig. 4. Prehistoric Rubber found 14 Miles from Sasco, Arizona.

But the earlier history of the industry in Mexico has a larger romance than can well be related in the short space here allotted. The more salient points only may be mentioned. Just as the Mayas in the south, and in the Amazon region, made playing 1 tails of latex rubber, so, in the north, guayule rubber was known and used by the aborigines. But the task of extraction was for these more indirect, for they chewed the bark of the plant, in order to separate out the fibrous tissue and to agglomerate the rubber. Assiduous mastication on the part of a sufficient number of devotees to pelota turned out in a short time a resilient if crude rubber ball. There is evidence that this plaything found its way by barter to the coast of the Gulf of California and probably the peoples to the north and east also obtained it. Fig. 5. Microscopic Appearance of Guayule Rubber in the Cells of the Rubber-bearing Tissue. It is a matter of unusual interest that the aboriginal Papagos used rubber. Late in 1909 an olla, or earthenware jar, was unearthed at some depth on the site of an ancient village near Sasco, Ariz. In it were two round masses of rubber which, aside from a vitreous and fissured external layer, still displayed the texture, resiliency and odor of a dry and almost resin-free product. A generous piece (Fig. 5) of one of the masses was presented to the writer by Professor A. H. Forbes, of Tucson, Ariz., for study, but the microscopic evidence does not support the most natural supposition that it is guayule rubber, but more probably that it is a latex rubber which found its way northward from the more remote parts of Mexico. It is fairly certain, therefore, that rubber was an article of barter over a rather wide stretch of country.

At the present time not only guayule, but two at least of its congeners, "mariola" (Parthe-