22 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
on a larger scale, as is now being done in Germany. The spruce, 
for instance, does not yield a satisfactory growth in many parts 
of Scotland, and this is also found to be the case near the sea- 
coast in other countries, as, for instance, in Schleswig-Holstein. 
Many parts of Scotland, also, do not offer what I would consider 
very suitable conditions for the growth of the Scots fir. True, 
rabbits will materially interfere with the success of the culti- 
vation of exotic trees and with forestry operations in general, but 
there is no reason at all why this difficulty should not be over- 
come. 
Not only do many of the exotic trees give a larger yield of 
timber than the indigenous species—compare, for instance, the 
yield of woods of Scots fir and Douglas fir of similar age at 
Scone—but they also furnish timber of superior quality. This 
point gains additional importance in view of the fact that the 
American supply of timber of many valuable species is within 
measurable distance of extinction. Scotland possesses the most 
favourable natural conditions for producing those high-class 
timbers which America will soon cease to supply. I regard 
the evidence of the successful growth of exotic trees in the 
parks of Scotland as of far greater national importance than 
the beautifying influence which these trees exert upon the 
landscape. 
With regard to one species, however, namely, Thuja gigantea, 
I would utter a word of caution. In Germany this tree grew 
well in its earlier stages, but it has now been attacked and 
largely destroyed by a disease due to a fungus called Pestalozzia 
Junerea. Unfortunately, I found that the specimens of this tree 
in the nursery at Dunkeld were attacked by the same disease, 
and at Murthly the Thujas were also suffering from this parasite. 
I am afraid that this disease will interfere with the extensive 
cultivation of Thuja gigantea in Scotland. Although the older 
specimens of this tree are proving resistant to attack, it is 
probable that the fungus will obtain the upper hand of the 
young plants. We find an analogous state of things in regard 
to the larch, old specimens of which are comparatively free from 
attack of the canker which is so destructive to the tree in its 
earlier stages. 
During my visit to Murthly I often put the question to myself, 
whether the trees which are showing such luxuriant growth in 
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