74 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



resembles in the Alps, but assumes a more straggling and looser habit, \ 

 consequent on the elongation of the many tiny stems which form the j 

 cushion. These modifications would appear to be due to the less intense I 

 light and to the less extreme alternations of high and low temperature j 

 prevailing in this country. 



The most instructive experiments are, however, those which have ' 

 been conducted by the two great botanists whom I have already quoted, j 

 Keener and Bonnier. Their expermients consisted in cultivating low- 

 land plants in the alpine climate, establishing, at the same time, control i 

 gardens in Vienna and Paris respectively for purposes of comparison. 

 Bonnier experimented in several different gardens : one at Paris 105 

 feet above sea level ; two gardens in the Mont Blanc range at 3460 i 

 feet and 7590 feet respectively ; and three gardens in the Pyrenees at 

 2470 feet, 4750 feet and 7920 feet respectively. By using the same ' 

 soil for the cultivation of his plants in each garden, he endeavoured, as 

 far as possible, to eliminate all variations of conditions save those attri- 

 butable to the climate. It is not possible here to set out in detail the 

 results of these very complete experiments which Bonnier conducted. 

 For these, reference must be made to his works. The general results I 

 of the observations made were, however, briefly, as follows: — Under 

 the influence of the alpine climate the axes of the plants became shorter 

 and the leaves closer together, and the general growth exhibited a ten- 

 dency to spread out horizontally. Where the plants were tomentose, j 

 or hairy, this characteristic became more strongly developed. The 

 flowers were more intensely coloured, and were often larger. The 

 roots of the plants also acquired a stronger development. These modi- 

 fications vary in extent in different species. In some cases they were, 

 comparatively slight, but in a few extreme instances the plants culti- 

 vated in the experimental alpine garden established at the highest alti- 

 tude only attained one-tenth of the height to which they grew in the 

 control garden in Paris. (Figs. 51 and 52.) 



Keener 's experiments were conducted in two gardens, one estab- 

 lished at Vienna, and the other on the summit of the Blaser, a moun- 

 tain in the Tyrol of an altitude of 7243 feet. His results were practi- 

 cally identical with those of Bonnier, f He, however, emphasizes the | 

 fact that in some cases he observed a bleaching of the vegetative organs \ 

 owing to the partial destruction of the chlorophyll, and in other cases j 

 that the colour of the foliage was concealed by a strong formation of I 

 anthocyanin. Kerner regards the production of anthocyanin by plants i 

 at high altitudes as one of the many protective devices which they | 



* Bonnier, (1) " Cultures experimentales dans les hautes altitudes." Compfes ! 

 rendus de L Academie des Sciences de Paris, Tome cxx, 1890; (2) "Influence des \ 

 hautes altitudes sur les fonctions des vegetaux," Ibid.; (3) "Etude experimen- \ 

 tale sur I'influence du climat alpine sur la vegetation et les fonctions des plantes." j 

 Bulletin de la Societe hotanique de France, Tome xxv., 1888; (4) "Etudes eur 

 la vegetation de la vallee de Chamounix et de la chaine du Mont Blanc." 

 Bevue generale de hotanique. Tome 1., 1889; (5) " Recherches experimentales sur I 

 Tadaptation des plantes au climat alpin." Annales des sciences naturelles, 

 1q serie, Tome xx., 1895 (6) "Cultures experimentales dans les Alpes et les 

 Pyrenees," Bevue generale de hotaniqt/e, Tome ii., 1890. 

 t Kerner, ojj. cit. vol. xi. pp. 507-511. 



