ORGANIZATION' PLANT MEMBERS. 35 I 



to meet and in the solution of them it has developed into a great 

 variety of forms. It is also Ukely that different plants would in 

 many cases meet these difficulties in different ways, sometimes 

 with equal success, at other times with varied success. Just as 

 different persons, given some one piece of work to do, are hkely 

 to employ different methods and reach results that are varied as 

 to their value. WTiile we cannot attribute consciousness or 

 choice to plants in the sense in which we understand these qual- 

 ities in higher animals, still there is something in their "consti- 

 tution" or "character" whereby they respond in a different 

 manner to the same influences of environment. This is, per- 

 haps, imperceptible to us in the different individuals of the same 

 species, but it is more marked in different species. Because of 

 our ignorance of this occult power in the plant, we often speak of 

 it as an "inherent" quahty. 



Perhaps the most striking examples one might use to illustrate the dif- 

 ferent line of organization among plants in two regions where the environ- 

 ment is very different are to be found in the adaptation of the cactus or 

 the yucca to desert regions, and the oak or the cucurbits to the land condi- 

 tions of our climate. The cactus with stem and leaf function combined in 

 a massive trunk, or the j-ucca with bulky leaves e.xpose little surface in 

 comparison to the mass of substance, to the dry air. They have tissue for 

 water storage and through their thick epidermis dole it out slowly since 

 there is but little water to obtain from dry soil. 



The cucurbits and the oak in their foliage leaves expose a very large sur- 

 face in proportion to the mass of their substance, to an atmosiihere not so 

 severely dr\' as that of the desert, while the roots are able to obtain an 

 abundant supply of water from the moist soil. The cactus and the yucca 

 have differentiated their parts in a \-ery different way from the oak or the 

 cucurbits, in order to adapt themselves to the peculiar conditions of the 

 environment. 



When we say that certain plants have the power to adapt themselves to 

 certain conditions of environment, wc do not mean to soy that if the cucur- 

 bits were transferred to the desert they would take on the form of the cactus 

 or the yucca. They could do neither. The\- \\ould yierish, since the change 

 would be too great for their organization. Nor do we mean, that, if the 

 cactus or yucca were transferred from the desert to our climate, thev would 

 change into forms with thin foliage leaves. They could not. The factis 

 that they are enabled to live in our climate when we give them some care, 

 but they show no signs of assuming characters like those of our vegetation. 



