75 



annual species from the plains which had had sufficient time and warmth to 

 develop seeds were longer lived on the top of Mt. Blaser since in the follow- 

 ing year, new sprouts were developed from the lower part of the stems. An 

 earlier blossoming could also be observed. 



Corresponding to the fact that the intensity of the sunlight increases 

 with increased elevation, the color of the blossom, depending upon the antho- 

 cyanin, also became more intense. Blossoms, which were white on the plains, 

 had in the Alps petals which were violet underneath. The glumes of grasses, 

 green on the plains, or only pale violet, became dark brownish violet in Al- 

 pine regions because of a more abundant formation of anthocyanin^ 

 The leaves of Sedum acre, S. album and S. hexangulare became purplish red. 

 On the other hand, leaves of Orohiis vermis, Valeriana Phu and Viola cucitl- 

 lata turned yellow from the excess of light in the Alpine experimental gar- 

 dens while in the valley in shaded places their foliage remains green. 



The mountainous region affects not only temperatures in the annual 

 seasonal average but especially the moisture content of the atmosphere. 

 Warmth and humidity in their total amount and in their distribution during 

 the seasons together with the supply of light are determinants of growth. As 

 already mentioned, atmospheric moisture influences the amount of light 

 available for the plant, for a humid atmosphere absorbs about five times as 

 many light rays as does a dry atmosphere. 



Since the absolute content of the air in water vapor decreases with the 

 elevation, less light will be absorbed in the mountains, especially since the 

 rays of light have a shorter distance to traverse in order to reach the earth as 

 compared with regions at sea level. The fact that the absolute vapor con- 

 tent of the air decreases with the elevation is a matter of course for, since 

 the temperature becomes lower and lower, the air must condense its water 

 vapor and give it off in a liquid form. But the relative moisture increases 

 in the mountains which explains why we call a mountain climate damp and 

 rainy. Cloudiness is also relative to the moisture of the air. 



This increase of the relative moisture and the decrease of temperature 

 form the reasons for the rapid ending of our cultural efforts so far as these 

 concern the obtaining of seeds in mountain regions. We know that the for- 

 mation of blossoms and seed requires an increase of warmth proportionate 

 to the length of the growth period. For this reason we find, as mentioned at 

 the beginning, that grain often does not ripen in the mountains and that 

 therefore clover and other legumes furnish an insufficient amount of seed. 

 Yet another condition must be added to those already mentioned, to which 

 Pax has called attention-, viz., that the insects are only half as num- 



1 The theory that anthocyanin is developed for the protection of the plant 

 against too strong sunlight is held by many investigators. Kerner (1. c. Vol. I, 

 p. 508) assumes that, in the reddening of blossoms which appears with a lack of 

 heat, the loss to the blossoms of the directly conducted heat is compensated "by the 

 heat obtained from the rays of light by means of the anthocyanin." We believe we 

 have observed that the red coloring matter indeed does develop abundantly with a 

 lack of heat, but can also set in with an abundance of heat if, in proportion to the 

 heat, an excess of light makes itself felt in the tissues which contain sugar. 



- Das Leben der Alpenflanzen. Zeitschr. d. d.-ostr. Alpenvereins 1898, p. 61. 



