xvi A. F. W. SCHIMPER 



explain the significance of the epiphytic habit and structure. In 

 the forests he noted that the least modified types were those living 

 in moist and shady crevices of the bark low down the tree-trunks, 

 and that the more elaborate ones lived in the drier but better 

 lighted situations higher up the trees. In the open country, 

 especially in savannahs, he observed that the few epiphytes grow- 

 ing on trees, and the lithophytes, were identical with the elaborate 

 xerophytes perched on the tree-tops in the forest. Thus he con- 

 cluded that epiphytes were derived from terrestrial forest- plants, the 

 key to whose evolution lay in the struggle to reach the light without 

 the expenditure of the material necessary to raise the leaves of 

 a terrestrial plant to an equivalently illuminated spot, and the key 

 to whose success lay in the successful adoption of a xerophilous 

 habit. Other observations showing the interchange of positions 

 among epiphytes, plants occupying shores, rocks, alpine heights, the 

 vicinity of salt-springs, and their absence from other intervening 

 spots confirmed the view that they are all true xerophytes. Again 

 appealing to the fact established by cultivation that shore-plants 

 grow equally well inland away from saline soils, Schimper was 

 able to draw the conclusion that they were salt-enduring xerophytes 

 driven to the shore by competition. 



Observations on the general distribution of types of vegetation 

 over the surface of the earth provide additional means of arriving 

 at important oecological conclusions ; for they deal on the one hand 

 with great climatic and other changes of the environment, and on 

 the other hand with more or less similar conditions prevailing at 

 widely distant spots. Schimper was thus able to point out that it 

 is a moist climate that determines the existence of phanerogamous 

 and vascular epiphytes, excepting where a cold winter steps in to 

 prevent the roots from absorbing water. Again, by comparing 

 tropical and temperate alpine plants he was able to show that cold 

 is not the controlling factor in the case of these xerophytes. 



The present work, his masterpiece, shows the manner in which 

 Schimper regarded plant-life. It reveals him, not as merely the 

 keen observer and subtle critic of Nature, but rather as her inti- 

 mate friend from whose watchful eyes and sympathetic mind she 

 cannot hide her mysteries. It reveals him, not as the idle creator 

 of airy hypothesis, which the first breath of fact can dissipate, but 



