126 PLANT WORLD. 



expedition at elevations above a thousand feet in Sonora and 

 Arizona, while a third, with a number of smaller heads in a 

 cluster, was seen nearer the Gulf of California. The larger 

 species often measure over five feet in height with a diameter 

 of more than two feet at the base, containing as much as 

 200 lbs. of water. This sap is only slightly charged with 

 substances ordinarily in solution in the plant cell, and an 

 Indian runner, striving to make a swift journey in Papa- 

 gueria, need not carry water with him, but may resourcefully 

 shape his way to meet with these "bisnagas" from which a 

 grateful supply of satisfying liquid can be quickly obtained. 

 Some travellers speak slightingly of the juice as a drink, and 

 magnify the difficulty of its extraction. It has, however, 

 proved useful on many expeditions, and if the thirsty traveler 

 is so fortunate as to be armed with an ax or a large knife, 

 he may secure a quart of liquid within seven to ten minutes. 

 Lacking these, he must burn away the huge spines and then 

 crush the top and pulp with a stone before the juice can be 

 squeezed with fingers into a centrally made cavity, a method 

 which may need twice as much time, but which might avoi^l 

 serious consequences from thirst in a region in which a man 

 at work uses as much as sixteen pints of water daily. 



Not all melon cacti can be expected to yield their store 

 of water so readily, however. Echuwcactus grande attains 

 the height of seven or eight feet, and a thickness of a yard 

 in the desert of Tehuacan in southern Mexico. The firm 

 pulp is heavily loaded with lime, so that when chewed it is 

 unpleasantly gritty; the juice is not obtainable by the methods 

 used with the Sonoran species. 



The route of the expedition lay almost due west from 

 Tucson for a distance of over a hundred miles, until the 

 northern end of the Ajo mountains was rounded and then 

 Sonoyta was made on the riv^er of the same name, across 

 the international boundary. Here during the remainder of 

 the trip, many interesting interpretations of place names de- 

 rived from plants were met, "Ajo" itself was found to mean 



