184 University of California Publications in Botany [Vol. 7 



T. OBJECT AND SCOPE OP^ THE INVESTIGATION^ 



The investigation here reported upon was instituted for the pur- 

 pose of locating: a supply of rubber which it was thought might exist 

 in certain native West American shrubs. Of all the various species 

 originally considered, those belonging to the genus Chrysothamniis, 

 commonly known as Rabbit-brush, seemed to be the most promising, 

 and consequently they have received the most attention. 



This work was undertaken immediately after the entrj^ of the 

 United States into the recent war and had for its incentive a considera- 

 tion of the following facts : that rubber is absolutely essential to mod- 

 ern warfare ; that it is the only war essential not now produced in 

 this country ; and that, therefore, we as a warring nation would be 

 seriously handicapped in case the enemy should be able to carry out 

 his threats and put a stop to our oversea commerce. This danger of 

 interference with our importation .of rubber has now been happily 

 averted but since no one is able to state with certainty that it may not 

 recur, the location of a native supply is still a matter of national con- 

 cern. Our studies have therefore been continued somewhat beyond 

 the duration of the war and have resulted, as indicated in the follow- 

 ing pages, in the finding of rubber of good quality in some of our 

 western shrubs. If it were all assembled the total amount (estimated 

 to be over 300,000,000 pounds) would be considerable, but the per- 

 centage content of the plants is too small to warrant harvesting except 

 under stress of national emergency. The very fact that the shrub is 

 not rich in rubber may have its advantages when the matter is viewed 

 from the standpoint of the nation's needs. It means that the rubber 

 will not be subjected to commercial exploitation and will thus be pre- 

 served as an emergency supply to be drawn upon only in case we reach 

 such straits that its utilization becomes necessary notwithstanding the 

 high cost of harvesting. 



The very best protection against the possibility of enemy interfer- 

 ence with our supply would be the development of a permanent rubber- 

 producing industry in this country. Aside from the manufacture of 

 synthetic rubber on a commercially profitable scale — a desideratum 

 which does not seem to give promise of early realization — our only 



1 This investigation was carried out t-hiefly by nicniberJi of the Department of 

 Botany of the University of California and was one of tlie jnojects of the Sub- 

 committee on Botany of tlie Committee on Scientific Researcli of tlie State Council 

 of Defense of California. 



