550 FREEZING AND BURNING. 



of mountain pines are therefore avoided and left alone, and many of them have 

 never been penetrated by the foot of man during their whole existence. Woe to 

 him who has the misfortune to lose his way in such a tangled wood! The difficulties 

 one has to encounter in a tropical primeval forest beset with lianes are not greater 

 than those with which one must struggle in attempting to press forward here. 

 Frequently the mountain pines grow so high that one is considerably overtopped 

 even when standing upright by the highest prickly branches. It is perhaps pos- 

 sible to make a little progress by climbing over the horizontal, arm-thick stems, but 

 it is vain to endeavour to find one's way and to gain an outlook. If we mount on 

 one of the curved ascending boughs in order to see above the highest branches, 

 the bough bends down to the earth under our weight, along with the stem from 

 which it arises, and we again sink despairingly into the sea of the dark-green 

 crowns. Just such a down-bending occurs, however, under the burden of the 

 winter snow. If then by chance the ordinary mantle of snow is added to by that 

 from avalanches, the pressure increases so much that the branches are pressed 

 down to the soil. This process may go on to such an extent that even many 

 branches, which in the summer stand a metre above the ground, lie in the winter 

 directly on the soil on account of the snow pressure. When the snow melts in the 

 following spring, and the branches are gradually lightened, they rise up again 

 in consequence of their extraordinary elasticity, and resume that position which 

 they occupied in the preceding summer. The process which is here carried on 

 automatically strongly reminds us of the manipulations of gardeners, who in the 

 autumn bend down rose-trees to the earth and cover them with non-conductors, 

 keep them in this position throughout the winter, and not till the next spring raise 

 them again and fasten them to erect sticks. In the summer the old leaves on the 

 ends of mountain pine branches, which wave above the ground more than a metre 

 high, may be frequently seen plastered over with earth and small stones, and 

 anyone knowing nothing of the processes above described would not easily under- 

 stand how these small stones had come to be fixed in these situations. As 

 a matter of fact the earth which lies on the branches through the winter, 

 moistened by the snow-water, forms the adhesive agent, which is so efficient that 

 stones more than 1 cm. in diameter are attached by it to the old tufts of leaves. 

 Many other Alpine shrubs behave like the mountain pines, as, for example, the 

 Dwarf Juniper (Juniperus nana) and the Alpine Alder (Alnus viridis). In like 

 manner the rhododendron bushes are also pressed to the ground by the snow, 

 although not to such a great extent, and are thus protected against the great 

 cold, and particularly against extreme radiation. 



In forest regions the dry foliage, which falls from the trees and overspreads 

 the ground and undergrowth to a greater or less thickness,, appears also to be 

 usually an excellent protective agent. This foliage layer is thickest in the beech 

 forests of Central Europe, and the sheltered plants include the Woodruff, Lungwort, 

 Hepatica, Asarabacca, Sanicle, and Waldsteinia (Asperula odorata, Pulmonaria 

 officinalis, Hepatica triloba, Asarum Europceum, Sanicula Europcea, and Wald- 



