Growth in Eriogonum nudum 237 



Aug. 29, beginning with 8 hr. rea ding; high fog all day. Hour periods. Uviol glass 

 till 14 hr. 



Rate: 20 o 19 7 -8 -5 glass removed 42 68 65 40 20 

 Temp.: 78 85 at 14 hr. 73 57 



The temperature remained high in the chanber (78-85 degrees) till 

 the removal of the glass, when it rapidly fell, with a raising of humidity. 



Aug. 30, beginning with 7 hr. reading. Red screen on at 8 hr. till 13.42 hr. Wilting 

 evident in controls at 14 hr. Sun till 10.45; dense high fog 11. 25-13. 25; sun till 13.55 



15 



Reduction of light did not prevent minus rates for two hours for 

 which high temperatures inducing transpiration were responsible. High 

 rates followed the removal of the red screen after a short interval of 

 8 min. which concluded a second period of shrinkage on this day. 

 Conditions were complicated by the intervention of fog, which, the 

 temperatures and humidity becoming more favourable, permitted more 

 rapid growth for a period, though the turning point was passed while 

 the sun was scill shining and the temperatures high. It is difficult to 

 see any dominating influence except that of temperature and humidity 

 and their efTect on transpiration. 



Aug. 31, beginning with 6 hr. reading, the chamber being closed with uviol glass till 



1715: 



Min.: 60 60 60 60 60 20 20 cool breeze at 20 20 20 20 60 



10.45 temp, dropped 



The reduced illumination at 13 hour was not followed by an increased 

 growth rate, which became rapid only in the late afternoon. It seems 

 clear that temperatures were controlling. 



The foregoing experiments in which the changes in illumination 

 were imposed on the growing part lead clearly to the conclusion that 

 these alone are of very minor influence on the rate, or on the total 

 amount of growth. We should probably, however, attribute a small 

 temporary positive effect to light within the normal range of insolation 



