414 Cannon: Transpiration of Fouquieria 



studied had no leaves. Within 48 hours after the rain of May 

 1 1 it was well covered with them. On June 29, in the midst of a 



V 



very dry period, three gallons of water were given to one speci- 

 men of Foiiqtiieria and leaf-buds were observed on July i, which by 

 2 P. M. on the succeeding day were i cm. long. On the fifth 

 they were of mature size. 



Fouqiiieria No. II formed five distinct leaf-coverings between 

 jFebruary and August. The exciting cause in each instance was 

 :an increase in the w^ater-supply. Very soon after the rains were 

 .over the leaves were dropped and excessive and destructive trans- 



-piration was thus avoided, 



8. The daily periodicity of Fouqnieria was observed in April. 

 The rate varied in a manner corresponding to variations of the 

 temperature, but not quite the same, and it inversely followed 

 very closely the variation of the relative humidity. 



Desert Botanical Laboratory, 

 Tucson, Arizona. 



