P. MACNAIR ON THE ALPINE PLANTS OF PERTHSHIRE. 
247 
conditions are favourable or otherwise to the establishment of these 
Alpine plants. Thus, mountains in proximity to or exposed to the 
influence of the sea are more favourable to the growth of certain 
species than those at greater distances or protected from the influence 
of the ocean—that some prefer an insular, while others prefer a 
continental climate. How far these conditions affect our Perthshire 
plants would, I think, be exceedingly difficult to say, as the two 
extreme types of continental and insular climates can scarcely be said 
to be sufficiently well marked within the region under discussion to 
enable us to argue with any degree of certainty as to the part which 
this factor has played in the distribution of our Alpine plants. Dr. 
Buchanan White, in referring to Axel Blytt’s theory in his address to 
the East of Scotland Naturalists’ Union, makes the following pertinent 
remarks:—“ Before we can accept this,” he says, speaking of Axel 
Blytt’s views, “as an explanation of the reason why certain plants 
occur in Clova and not in Breadalbane and vice versa, the peculiarities 
of the distribution of each plant in countries where the difference of 
climate is more marked must be investigated, since it may turn out 
(and in some cases I have reason to think that it will turn out) that 
the facts do not agree with the theory.” 
It has long been suspected that geological structure and the 
nature of the rocks upon which these plants are to be found has 
played an important part in their distribution, thus we find Dr. Hugh 
Macmillan describing the rocks of Canlochan as composed of friable 
mica schists, which are well adapted for the growth of these plants. 
Botanists have also long been familiar with the highly micaceous 
nature of the rocks and soil of the Breadalbane ridge of mountains, 
making, as it does, a sure index of the locality from which the plants 
have been taken. And so thoroughly do these plants seem to become 
saturated, so to speak, in this micaceous soil, that the particles of 
mica adhere to them long after they have been pressed and placed in 
the herbarium. Dr. Buchanan White, in the address which we have 
already frequently cited, while pointing out that the influence of the 
rocks and soils upon these plants had already been partly investigated 
without any satisfactory results, believed that much was yet to be 
done in this direction, and advocated the conjoint study of this factor 
by botanists, mineralogists, and geologists. What further advances 
have been made in this direction will be the subject of the remaining 
part of our paper. 
It has now become known, and that principally through the de¬ 
tailed mapping of the Geological Survey, that along the line of these 
mountains stretching from Ben Lui to Clova we have an outcrop of a 
well-marked band of schistose rocks whose significance as a factor in 
the distribution of our Alpine flora, I now venture to think, rests 
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