The Environment. 15 



Table i. Rainfall at Cedros, September 1907 to August 1908 (fig. 3). 



Note. It seems probable that the rainfall for the four months of 1907 was 

 relatively high, and includes an amount which normally would have been distrib- 

 uted earlier in the year, that is, in the summer months. 



I visited Cedros during April 1909. Upon arrival there it was found 

 that there had been no rain, save a few drops on a few occasions, be- 

 tween August 20, 1908, and April 5, 1909. On the latter date heavy 

 showers occurred over considerable areas, leaving water standing in 

 "charcos" for several days. This was a very persistent drought, and it 

 was found to have affected guayule quite unfavorably in many localities. 

 I am informed by Mr. G. R. Fleming that drought again persisted till 

 June 16, 1909, when it was broken and a very abundant rainfall ensued 

 during the summer of 1909. 



AIR-TEMPERATURES. 



Table 2 shows observed temperatures at Cedros during the time 

 indicated. The lacunae observable in May, June, July, and August are 

 not as fatal to an adequate notion of the prevailing temperatures as 

 might be supposed. A brief study of the table as a whole will show that 

 the temperatures are remarkably uniform, and this is especially true of 

 the months for which data are lacking. The readings, therefore, which 

 were made nearly every day, were not recorded except as they showed 

 variations of several degrees. 



The lowest temperatures to which guayule may be subjected are 

 not known. The minima at Cedros are undoubtedly higher than those 

 which occur in the guayule region of Texas, but as meteorological data 

 for that region are lacking we are compelled to judge by those of El 

 Paso, the nearest station. The minimum temperatures observed here 

 during the last twenty years range close to zero, so that we may infer 

 that the guayule plant can withstand lower temperatures than those 



