THE CACTUS FORESTS OF CENTRAL BOLIVIA 325 



of giant humming-birds {Patagona gigas) came to sip nectar 

 from these flowers. 



The mountains seem formed of solid sandstone. Here 

 and there a ledge, worn and rounded by the elements, pro- 

 jects conspicuously and resembles an impregnable fort or 

 castle of majestic though fantastic design. We reached a 

 lone Indian hut late at night, and, while the arriero was 

 loath to halt, the mules were too tired to go much farther. 

 The neighborhood was in bad repute on accoimt of a num- 

 ber of robberies and murders that had recently taken place 

 there, and not long after our arrival we saw mysterious 

 signal-fires spring up on the surrounding slopes. We there- 

 fore camped in a corral, the enclosing stone walls serving 

 as a barricade, and alternately did sentry duty throughout 

 the night. I believe one of the reasons for our being left 

 severely alone was that each member of the expedition 

 was advised to display casually his pistol to the inhabitants 

 of the hut, and to acquaint them with its possibilities. 

 This same ruse has prevented serious trouble in a number 

 of instances. I have foimd that by far in the greater part 

 of South America there is not the slightest necessity of 

 carrying a weapon of any kind; but there are isolated re- 

 gions where the moral effect on the natives produced by 

 wearing a revolver of generous size in a conspicuous place is 

 so great that one may tread with impvmity what would 

 otherwise be dangerous ground. 



The next night was spent on the banks of a narrow creek 

 called Usiamayo, the elevation being only seven thousand 

 nine hundred feet. Many Indians live on both sides of 

 the stream. They own numerous flocks of sheep and goats 

 and cultivate extensive areas of maize and wheat. Their 

 huts are low, primitive affairs, and of such small size that 

 they resemble overcrowded rabbit-hutches. Freshly cut 

 grain was piled in neat heaps that were surrounded by 

 fences of thorny brush to keep the sheep and cattle away. 

 Com fodder was stored in the tops of low trees. From a 

 distance these aerial storage-places looked as if they might 



