CONTRIBUTIOX OF THE SCIENCES 243 



geological record. The geologist who views the history of crustal move- 

 ment considers that there is no reason for believing that the crust is now 

 stabilized, and that we may expect other movements and other earth- 

 quakes. "We know fairly the physical laws that govern earthquakes. We 

 can prepare to meet them in such a way as to eliminate most of the dan- 

 gers incident to their action^ but it will take the passing of another 

 generation before we reach a stage in which the clear lessons of earth 

 history bearing on interpretation of these phenomena will become the 

 basis of common practice, such as dictates the precautions which have 

 made it possible for us to build in the summer against the rains of autumn 

 and the snows of winter. Many of us still build as if the last earth- 

 quake suddenly ended the series measuring back for tens of millions of 

 years. 



Still more difficult may it be for us to make use of the lessons of pre- 

 liistoric history relating to our adjustment to biological environment. 

 In America we live largely on plants and animals of Old World origin, 

 not because the abundance of these types is so much greater than that of 

 America, but because man has lived a longer time in the Old World, and 

 within the period of his early history, reaching back to past geological 

 periods, he has experimented intentionally or accidentally with Old 

 World plants and animals for a longer time than has been given to con- 

 tact with the native life of America. There are many who do not recog- 

 nize this relation to the world of undomesticated organisms about us, 

 and seem to feel that some plants and animals were predetermined to 

 domestication, while others can never serve us. 



Left to chance, as during past millenniums, we may in time develop a 

 series of useful American plants and animals corresponding to those of 

 the Old World ; or, recognizing the significance of the historical explana- 

 tion of our relation to domestication, we may by active and carefully 

 directed research secure results comparable to those of a long period of 

 casual or accidental contact, and obtain a great variety of wild forms 

 for use to meet human needs. Such an example of possibilities seems to 

 be found in the development of the desert rabbit-brush as a source of 

 rubber. An investigation was undertaken as an emergency problem 

 during the World AVar, when there loomed before us the possibility that 

 submarine dominance would eliminate all possible rubber importations. 

 "Recent studies by Hall and Goodspeed have shown the presence of 

 300,000,000 pounds of rubber in the desert region of the West. At present 

 prices it is not available. In an emergency it might be a facto/ of first 

 iinportance contributing to defense of the nation. Future research may 



