190 GUIDEBOOK OF THE WESTERN UNITED STATES 
pitahaya, and agave, besides acorns and camote, an edible root, are 
important food resources, especially in poor seasons; formerly there 
was considerable game. One of their principal trading commodities 
is salt, which they gather from lagoons on the shore of the Gulf of 
California. The Papagos are divided into clans, two of which are 
included in the “‘red velvet ants,’ who are regarded as the original 
owners of the country, and the others in the ‘‘white velvet ants,” 
who have come later. Descent in these clans is by the male line, 
which is contrary to the custom of the Pueblo Indians, The Papagos 
of San Xavier apparently absorbed the Sobaipuris, the last of whom, 
Encarnacién Mamaxe, died at San Xavier Mission early in 1932, at 
the age of 106 years. The Papagos regarded the sun as the “ Father,” 
and their principal deities were the ‘‘Elder Brother” and the “ Rarth 
Magician,” but most of them are now Catholics. 
The Desert Laboratory occupies 860 acres on the Tumamoc Hills 
in the western part of Tucson. It was established in 1903 with the 
belief that this location offered the greatest opportunities for studying 
desert vegetation and the problems of its growth, its enemies, and soil 
relations. In 1905 it was made the headquarters of the department 
of botanical research of the Carnegie Institution of Washington. It 
has obtained a large amount of most valuable information regarding 
plant growth, soils, and water conditions in the desert. The State 
Agricultural Experiment Station at the university has branches in 
various parts of Arizona, studying many problems of crop, fruit, cotton, 
and nut production. 
Tucson obtains its water supply from wells that draw from the 
underflow of the Santa Cruz Valley south of the city. In the Rillito 
Valley (ree-yee’toe), just north of Tucson, underground water is 
pumped for irrigation. When old Fort Lowell was located in this 
valley, at the mouth of Pantano Wash, the cavalry horses were fed 
with hay cut from the flood plain, which is now dry and deeply 
trenched. 
From Tucson a branch line of the Southern Pacific system ascends 
the Santa Cruz Valley to Nogales, on the international boundary, and 
thence goes to Guaymas (10 hours), Guadalajara (48 hours), and 
Mexico City (65 hours). At 44 miles south of Tucson it passes the 
ruins of the old Spanish presidio of Tubac, which dates prior to 
1752 and was erected to protect the neighboring missions. At 
this place in 1858 to 1860 a small group of Americans and Mexicans 
partly restored the ruins and published the “Weekly Arizonian,” the 
first newspaper in the Territory. A short distance beyond Tubac is 
the old Tumacacori Mission (too-ma-ca’co-ree), established by Father 
_ Kino in 1702, now a most interesting national monument under Gov- 
ernment protection, | 
