466 CONIFERiE. 



at first, is closed and protected by a red velvety-looking 

 substance. If opened in this state, a nest of small greenish 

 aphides is distinctly visible, and at a certain period, or 

 when they have acquired maturity, which is towards the 

 end of summer, the mouth of the cell opens, and the insects 

 fly off to inflict a similar injury upon the nascent buds of 

 the year. In some instances, the leaves of only a portion 

 of the circumference of the shoot are affected, in which 

 case, though a slight distortion may take place, the branch 

 is not prevented from elongating ; but in others, where 

 the whole of the leaves around the shoot are converted 

 into nidi, elongation is prevented and distortion to a great 

 extent takes place. It is worthy of remark, that the 

 leading shoot is rarely, if ever, affected, the attack being 

 confined to the buds of the lateral branches. 



At Twizell, about forty years planted, it is sixty feet 

 high, the circumference of the trunk, at three feet from the 

 ground, six feet six inches ; and thirty years planted is 

 about fifty feet high, circumference, at one foot above the 

 ground, five feet two inches. 



Before closing the account of the Abies excelsa, we may 

 remark, that two species of the genus Abies have been 

 introduced frorn North America, and cultivated as orna- 

 mental trees for the last fifty or sixty years ; these are 

 the Abies alba and Abies nigra, the White and the Black 

 Spruces, so called from the colour of their respective foliage. 

 Both of these are of inferior growth to the Common Spruce, 

 with a close thick foliage and narrow cone-like forms. 

 From the shoots of the Abies nigra is obtained the essence 

 or extract of Spruce used in England in the making of 

 Spruce beer, for which purpose the shoots themselves are 

 used in America. Like Abies excelsa, the extremities of 

 the lower branches of Abies nigra, when they touch the 



