84 



foliage from altitudes over looo m. above sea level was noticeabl}' less than 

 in that from lower levels. The latter showed, however, in its ash, a smaller 

 amount of potassium, phosphoric acid and sulphuric acid, while the leaves 

 collected in altitudes were proved to be as rich in these substances as the 

 young foliage. The distribution of calcium and silicic acid v/as the opposite. 

 The size and weight of the average leaves decrease with the elevation. In 

 regard to morphological changes, H. Hofifman^ states that the young sprouts 

 of Sali.v herbacea and S. reticulata transplanted from high mountains to low 

 levels grow erect instead of lying flat on the soil. When moved from low- 

 lands to high mountains, Solidago J'^irga aurea becomes an aenemic dwarf. 

 riantaga alpina is a meagre mountain form of PL maritima not coming true 

 to seed and with short ears. The length of the ears increased in the second 

 generation on the lowland from 15 to 18 mm. ; the leaves became broader and 

 even serated ; there were fewer blossoms at this altitude but not smaller. 

 Hieraciun alpimim developed on the lowland isolated specimens with tall, 

 much branched stems. Aster alpinus in isolated examples developed broad- 

 er leaves. Gnaphalium Leonio podium, the Edelweiss, loses on the plains its 

 little inflorescences and pubescence. 



The facts ascertained when the larch was brought from the mountains 

 to the plains seem to be a very sharp warning to consider more caiefully the 

 natural requirements of the trees and not to believe, because possibly sup- 

 ported by soil analysis, that each tree must thrive where nutritive substances 

 are abundantly present for it. The great physical conditions, such as venti- 

 lation, illumination and dampness, are determinative factors which, taken 

 under due consideration, preserve the natural immunity of the tree and 

 make superfluous a petty local comliatting of the parasites. 



Lack of .Success with Tropicai. Plantations. 



Like every nation at tlie beginning of its colonizing period, we must 

 recognize that great loses occur in newly organized tropical plantations. An 

 essential factor for the protection from agricultural injury is to be found, 

 we believe, in the insignificant consideration of the native conditions of 

 growth from which the tropical useful plants originate. In regard to the 

 transplanting of plants from the plains into an altitude, the increase in the 

 relative dampness is of especial importance, next to the decrease in temper- 

 ature. These conditions, for example, quickly place a limit for the culti- 

 vation of grain. According to Fesca's reports (1. c. p. 42) grain species do 

 not flourish at all in the lower regions of the tropics and the ripening of the 

 grain becomes uncertain in the higher regions. In Java and Ceylon, culti- 

 vation of our species of grains and Leguminoseae with a view to raising 

 seeds becomes doubtful, even at elevations of scarcely 2000 m. 



On the other hand a smaller difference between the temperatures of win- 

 ter and summer is of great value, especially to tropical plants. Many plants 



Riickblick auf meine Variationsversuche, Bot. Z. 1881, p. 431. 



