22 THE FUTURE OF ARID LANDS 
utilize it as soon as possible by a crop adjusted in its demands to 
the supply of moisture in hand. 
We have by no means fully utilized the highly adjusted plants 
of the arid lands so rich in fibers and valuable chemical com- 
ponents. Duisberg (4) has pointed to many of them, but the 
field is still largely unexplored. Esparto and guayule are examples 
of useful products developed by nature in this zone. In this field 
M. C. Caldwell of the University of Arizona has found most 
promising antibacterial compounds which indicate that these 
desert plants have produced many substances which may fit into 
the important field of antibiotics. The genetic work of Gordon 
Whaley of the University of Texas points to a great resource of 
genetic material in the grasses of this arid belt. These are only a 
few examples of what seems a promising field of research. There 
are probably many chemical components developed in these 
drought enduring plants not present in plants grown and de- 
veloped under a less exacting environment. 
We know far too little from the standpoint of physiology and 
water economy to attempt a reasonable management of range 
plants. The plants that are the largest and produce the most 
forage are favored in the management with no questions asked 
as to the economic use of the valuable water supply. To choose 
the largest may be very misleading. If A, B, and C are grown to- 
gether in the same soil mass we may choose A with a water re- 
quirement of goo as a better plant than B with a water require- 
ment of 600 or C with a water requirement of 300 pounds of water 
to one pound of dry forage. In this case by choosing the plant 
on the basis of production, we are choosing the least efficient 
plant of the three. Not until we have a physiological balance sheet 
of the principal components of the range can we separate the in- 
eficient from the efficient. 
We also know far too little of the water balance of animals. In 
attempting to improve the food supply for the Navajos the prairie 
dog was poisoned and destroyed in the area. But to the Navajos 
the prairie dog is a delicious morsel. We do not know that the cow 
or sheep can produce as much food with a ton of grass as can the 
prairie dog. 
Primitive man used the rodents as an important food supply. 
