Biological histihitions 81 



rapidity between 1300 and 1350 A.D. Thus from California 

 to China evidence of various kinds unites to indicate that 

 during the fourteenth century there occurred a short period 

 of unusual stormiuess. Such conditions, if intensified and 

 prolonged, would probably cause the accumulation of enor- 

 mous glaciers. ' ' ^ 



Professor Huntington's studies on the influence of climate 

 upon human life form one of the most interesting and valuable 

 contributions to history of recent years. He has shown for 

 example that the wonderful civilization of the Mayas in 

 Guatemala and Yucatan, in a region where today death stalks 

 through the jungle and human energy is at its lowest ebb, is 

 explicable on the hypothesis of a different climate in these 

 regions in past years, an hypothesis supported by his evidence 

 obtained from lake and tree. He has similarly traced the 

 histoiy of man in Asia and Europe and likewise discovered 

 there the profound influence of nature upon his ways. 

 These climatic changes appear to be in some way determined 

 by solar activity as evidenced by the number of "sun spots." 

 But these most interesting hypotheses would lead us too far 

 aside from our proper path were we to pursue them further. 



Much of Professor Huntington's work was carried on 

 through the Department of Botanical Research, and his 

 results are among the most interesting and valuable of its 

 contributions to science. 



On a small tract of land in the Santa Cruz Valley belonging 

 to the Department are the experimental gardens, where for 

 a number of years Professor Tower of the University of Chi- 

 cago has been conducting his experiments on the potato 

 beetles, reference to which is made elsewhere. In the physico- 

 chemical laboratory extensive investigations are in progress 

 on the physical and chemical factors involved in the process 

 of photosynthesis ; or the work of the sun through the chloro- 

 phyl of the green plant in taking the raw materials of earth 

 and air and Avater and constructing from them the starches 

 and the sugars which the plant uses as its food. Many other 

 are the activities of the Department which occupies a unique 

 and indispensable place in American research. 



Surrounded by the blue waters of the tropical sea, 

 scorched by the sun, deluged by the torrential rains and 

 swept by the cyclones of the tropics lie a string of little 

 islands off the southern extremity of the coast known as the 

 Florida Keys. On one of the gi-oups, named by the early 

 Spaniards, from the abundance of their aboriginal inhabitants, 

 the sea turtles, the Dry Tortugas, is located the Department 



^Huntington, "Civilization and Climate," pp. 235-7. By permission 

 of the Yale University Press. 



