THE SILVER FIR. 



391 



to the branches. The buds, which are situated at 

 the extremities of the shoots, expand in spring, 

 and the young leaves are of a pale green, almost as 

 delicate as the tint of the primrose. I have ob- 

 served that the Sulphur butterfly, which makes its 

 appearance about the same time with these tender 

 shoots, loves to settle on their under side, either 

 attracted by their flower-like semblance, or taught 

 by instinct to rest where its enemies may be un- 

 able to distinguish its yellow wings from the sur- 

 rounding foliage. If driven from one of these 

 places of retreat, it flies a short distance and 

 alights on another. 



The Silver Fir was called by the Romans Abies, 

 a name which, by an error of the early botanists, 

 was given to the Spruce Fir, and hence consider- 

 able confusion has arisen. It was much used by 

 the ancients in ship-building, and was considered 

 by Virgil the fairest ornament of the mountains. 

 It is a native of the mountainous parts of central 

 Europe, and of the west and north of Asia, but 

 does not extend so far north as the Spruce or 

 Scotch Fir, nor, from its preferring a milder cli- 

 mate, is it found at so great an elevation as these 

 trees. In dimensions it is one of the most strik- 

 ing of the tribe, rising frequently to the height of 

 a hundred and sixty or even a hundred and eighty 

 feet, with a stem perfectly erect and generally 

 clothed from the base to the summit with regular 

 tiers of horizontal branches, and often measuring 

 as much as six or eight feet in diameter. For 

 many years the bark is smooth and of a greenish 

 grey colour ; but as the tree gains age, it becomes 

 rough, with small fissures ; and when very old it 

 often throws ofi" the outer part in large flakes, 



