40 



THE FACTORS 



[Part I 



the temperature went below -46' C. The individual in question grew on the top 

 of a fairly high sand hillock near Pittlekaj, exposed to the constant and cutting 

 north or north-east wind. It had commenced to blossom in the summer of 1878, 

 but its blossoming was far from being completed when the winter came on and 

 stopped further progress. Its system of flowers consequentlj' included flower-buds 

 in various stages of development, recently opened flowers, blown flowers, and some 

 more or less ripened fruits. Only an insignificant shrivelled remnant of the basal 

 rosette of leaves remained, but the upper leaves were fresh and vigorous. In this 

 condition the plant was overtaken by winter, and exposed to its utmost rigour. 

 We might well believe that it must have been killed, and especially that the tender 

 flowering parts which were attacked during their development would have been 

 destroyed by the frost and so prevented from developing further. This, however, 

 was not the case. When the summer of 1879 began, the plant continued its growth 

 from the point at which it had been arrested by the approach of winter ; the flower- 

 buds opened, and from the axils of the fresh upper stem-leaves fresh inflorescences 

 sprouted forth.' 



The fact that the coldest known places on the earth lie within the 

 Siberian forest-district is sufficient to prove, in the first place, that vegetative 

 organs can endure without injury temperatures lower than those observed 

 by Kjellman ; and, in the second place, contrary to a widespread but 

 unsupported view, that tree-growth is by no means excluded by prolonged 

 and severe winter-temperatures. Within the district just mentioned is 

 included, for instance, Yakutsk, where the thermometer not infrequently 

 sinks to - 62° C, and Verkhoyansk, which is, if possible, still colder. Details 

 concerning the temperature of the latter place are given in the following 

 table 



