INDUCTION OF LEAF FORMATION IN OCOl'lLLO. 



57 



extent of adaptation, as evidenced by anatomical structures, to 

 which plants have attained in this matter. It was during a con- 

 versation upon such points with Dr. W. A. Cannon at the Desert 

 Botanical Laboratory that the suggestion was made by him that it 

 would be instructive to see if any light could be obtained upon 

 the influence of meteoric water upon the development of leaves 

 in Foiiqiiicria splcjulciis, the ocotillo of the southwest. I accord- 

 ingly planned three experiments which were carried out upon a 

 perfectly leafless plant, all alike in prinicple, but differing in de- 

 tails. In one case, the only one I shall describe, a reservoir, con- 

 sisting of a gallon bottle, was attached to the neighboring limbs 

 of a " palo verde," and a siphon arranged to lead water to a string 

 of cheese-cloth, which in turn led the water to a bandage of the 

 same cloth tied about a stem of the ocotillo three feet from the 

 ground. The fierce winds several times played havoc with my 

 arrangements, but finally I managed to adjust the apparatus to 

 the swinging of the stems by allowing slack in the cheese- 

 cloth string. The siphon ended in a capillary tube, so that the 

 flow of water was small, and while it ran down the ocotillo stem 

 at times, it did not reach the ground in anv case. The reservoir 



Fig. 9. fouqitlLria splciuh'iis — the same as in I'lg. 8, three days after a rain. 



