96 Forestry Quarterly 



accompanying each scale furnishes the best means of distinguishing 

 the species. Of the ten firs in the United States only A. concolor 

 and A. grandis can not be so separated, but these are easily 

 recognized by their foliage. A compact key based upon the 

 bract characters summarizes this information for field use. 



Another key is given, based upon leaf characters alone, but only 

 six specjes can be so separated. A feature of both keys is that no 

 characters are used which are not readily observable by the 

 unaided eye. 



Following the systematic portion of the paper, the text includes 

 a serial treatment of each species, covering characters of foliage 

 and fruit, tree size, and geographical distribution. A page of 

 excellent drawings makes clear the leaf and bract characters used. 

 A very valuable check list of nomenclature is appended. 



A Conspectus of North American Firs {exclusive of Mexico). Proceedings of 

 Society of American Foresters, Volume IX, No. 4, October, 1914, pp. 528-538. 



A case of girdling a forked pine tree, 

 Effects similar to that described in Forestry 



of Quarterly, vol. XII, p. 559, is cited 



Girdling by Hartig. 



"The tree was 118 years old, and the 

 trunk was forked at 43^^ meters above the soil into two approx- 

 imately equal stems. The bark was peeled off all round one of 

 these stems at about 3 meters above the point of forkmg. When 

 the tree was felled eighteen years after this ringing operation had 

 been performed, it was seen that the crowns of both stems were 

 still sound, but that the foliage of the ringed stem was thinner and 

 weaker than that of the other stem. It was also foimd that growth 

 in thickness had practically ceased after ringing on the side of the 

 trunk situated below the ringed branch. The reason for the long- 

 continued life of the ringed stem is that the roots attached to the 

 base of the trunk on the side below the intact stem had received 

 normal nourishment, and therefore, having remained healthy, 

 had been able to supply the trunk with a good supply of water." 

 In case the girdling is not confined to the bark but takes in some 

 of the wood, the result, according to Strasburger's experiments, 

 depends on whether a sap wood tree or a heartwood tree is involved. 

 "Two beech trees 150 years old had trunks 32 centimeters in 



