116 . Transactions. — Botany. 



changes to alterations of level. Indeed, the most with which 

 we can credit the movements referred to is that they may 

 have helped to bring about the fluctuations of temperature 

 wliich took place, the minor acting in conjunction with the 

 major cause. 



By picturing to ourselves an extension southward of the 

 Arctic regions, and a consequent narrowing of the temperate 

 zone, with a subsequent movement in the opposite direction, 

 we shall probably obtain a fairly correct idea of the climatic 

 changes which took place in Europe between the commence- 

 nient of the quaternary epoch and our own time. Obviously 

 the effect of those changes, as selective and differentiating 

 agencies, on the vegetation of the region must have been very 

 great. As the temperature lessened, the power of endurance 

 in every species would be tested to the utmost, and all the 

 phenomena displayed by plants under the influence of cold 

 would be exhibited, such as the dwarfing - down and the 

 assumption of the deciduous habit, or, to borrow a term 

 frona the zoologist, passing into a state of chill coma. 



During this ordeal many species would inevitably perish, 

 and some hitherto evergreen would become deciduous ; thus 

 the proportion of the latter to the former would be increased. 



Here the question naturally arises, would the deciduous 

 tree have any advantage over the evergreen while these 

 climatic changes were taking place ? Or, to put the question 

 in another form, beside the mere loss of vital energy, would 

 the evergreen tree suffer in any way through the lowering 

 temperature while the deciduous form escaped ? This, I 

 think, may be answered in the affirmative ; for in the wdnter 

 of 1860 a light fall of snow which visited the Pelorus Valley 

 destroyed numbers of trees throughout the bush, owing to 

 their not being able to sustain the unusual weight. Judging by 

 what then happened, I am satisfied that, were a tithe of our 

 winter rainfall converted into snow, the mixed forests in this 

 district would completely disappear in a few years. On the 

 destruction of the larger trees would follow the death of the 

 undergi-owth to which they afford shelter, and which in turn 

 protects the all-pervading surface-roots of its protectors. 



Once broken into, and the surrounding conditions per- 

 manently changed, our mixed forests are doomed : this the 

 effects of the removal of timber for commercial purposes and 

 the running of cattle in the forests daily teach us. 



None of our deciduous trees except the generally-diffused 

 Fuchsia excorticata being found within the j)recincts of the 

 bush suffered from the fall of snow referred to. Their slender, 

 naked branches could not accunmlate a sufficient weight to 

 cause breakage ; while, not being overshadowed by loftier 

 trees, they did not incur danger from falling timber. Our 



