64 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY, 



yet there are dangers. Thus the Armillaria tnellea, which is 

 so deadly to conifers, flourishes on old beech stumps. The 

 colour being no certain guide by which to tell the Pacific from 

 the Colorado Douglas the author cites the fact that, in their own 

 country, the latter throws up its branches at an angle of 45", 

 while the branches of the former are horizontal. On Southern 

 slopes the Douglas requires a little shade, whereas this is not 

 necessary on Northern slopes. The author gives to the 

 Scotsman, Mr John Booth, the chief credit for the introduction 

 of this species. Booth energetically pushed it in the face of 

 much opposition. No one now doubts its value ; the German 

 States have been very thoroughly converted, and are introducing 

 it vigorously. Not Germany only, but many other countries 

 also, have followed the example of Scotland. The author, 

 while admitting the far greater growth of the Pacific variety, 

 considers that the Colorado variety has not been so closely 

 observed. He quotes Mayr as preferring the Colorado Douglas 

 where the climate is not maritime, or, failing that, where light 

 lateral shade is not available; this variety is less exacting 

 as to the degree of air-humidity, and of cover. The Douglas 

 will stand a great degree of cold well, and the Colorado variety 

 appears to do so the better of the two, but this is really due 

 to the fact that the Pacific variety has a habit of reshooting 

 in August and September, so that these shoots are weak against 

 cold. M. Barbey says that the Pacific variety has now been 

 conclusively shown to grow well in all soils, except in too limy, 

 wet, or meagre ones. It has even been known to thrive in the 

 stiffest clay. The nearer it approaches to the sea the better its 

 growth, for a high degree of air-humidity suits it. 



M. Jolyet, a forest officer charged with experiments at Nancy, 

 also writes of the Douglas. His main contention is that the 

 Pacific Douglas requires considerably more humidity than the 

 Colorado, and that this fact renders the latter variety more 

 suitable for the greater part of the Continent. We, in the 

 United Kingdom, may, fortunately, employ the faster-growing 

 variety. The Douglas has a wonderful range without its fast- 

 grown wood ceasing to be valuable, which is not the case with 

 most conifers. M. Jolyet quotes Dr Mayr as saying that " from 

 a forest point of view the Colorado Douglas is the tree of a 

 Continental climate, and of the plain, with its extremes of 

 temperature and humidity ; while the Pacific Douglas is the tree 



