82 



lain an insight into its material composition from the works of \\^eber^ 

 He studied sections of the trunk and the needles of the larch picked in 

 October in the Bavarian Alps, in the Spessart, from the plains of the valley 

 of the Main etc. Tn spite of the soil differences, the results agreed entirely 

 in regard to the influence of elevation. A\'eber summarizes these as follows : 



The organic substance of the needles increases with noteworthy regu- 

 larity with the absolute elevation of the habitat while the content in pure ash 

 decreases. The amount of ash becomes absolutely greater if the larch grows 

 on the plains or in moderately high mountains so that therefore to produce 

 an equal amount of burnable substance, more and more minerals are taken 

 up by the plant, as its cultivation descends into the plains. The most im- 

 portant elements of the ash, potassium and phosphoric acids, show a regular 

 increase in specimens from the plains in contrast to Alpine Larches. In re- 

 gard to the calcium content, the larch of the plains indeed excels, yet the, 

 constitution of the soil seems to be very determinative here ; magnesia and 

 sulphuric acid show an insignificant increase, while ferric oxid and silicic 

 acid show a considerable increase. 



It may be perceived from. Weber's investigations how very greatly the 

 life habits of this high mountain tree and its mineral composition change 

 with its descent to the plains and the question now becomes pertinent as to 

 whether the anatomical structure is not also changed by the entirely differ- 

 ent conditions of life on the plains. Primarily the plains offer strong con- 

 trasts from the most intense heat of summer to the great cold of winter. To 

 this must be added a lengthened spring with the summer-like days which 

 sometimes begin in February, always in March, and the subsequent relapses 

 to cold weather. However, the autumns of the plains may be of decisive sig- 

 nificance when a relati\ely warm, dam]) period not infrequently lasts into 

 December and does not permit the cessation of vegetation. One needs think 

 here only of our oaks and apple trees which often enough retain tlicir 

 foliage on the tips of the brandies throughout the whole winter. In apple 

 trees, especially in trellis and trained forms, many varieties did not develop 

 any terminal bud in autumn but the last leaf simply remains in the winter 

 in an unformed stage of development. 



In the larch these long, wet and relatively warm autumns stimulate 

 growth so that after the normal summer end of the annual ring, a few layers 

 of spring wood are formed, as I have often observed. Therefore in such 

 cases on the plains the beginning of an absolute dormant j^eriod (which 

 Kirchner emphasizes as necessary for the normal development of the larch) 

 does not take place and the immediate results will frequently be the loss of 

 the normal or usual resistance to frost. The frost wounds make possible the 

 entrance for all wound parasites which, in the often dense growth of larches 

 on the plains and the moist motionless air, find the most favorable environ- 



1 "Weber, R., Einflufs des Standortcs auf die Zusammensetzung der Asche vein 

 Larchen. Allg-em. Forst-u. Jagdzeitung 1873, p. 368 nnd in Biedermanns Centralbl. 

 f. Agriculturchemie, 1875, p. 336. 



