THE STKM. 



19 



is usually called the Trunk, furnishes the wood which is em- 

 ployed for fuel, and in the arts In respect to size, texture, 

 hardness, durability, color, and specific gravity, there are 

 wide differences in the wood of different species of trees. 

 Some trees stand and grow during the lapse of ages. Oth- 

 ers are comparatively short lived and begin to decay soon 

 after they arrive at maturity. Some attain, both in height and 

 bulk, to an enormous magnitude, while others never grow 

 higher than a few feet, or even inches, having trunks nc lar- 

 ger than straws. It is said that certain species of the Fig- 

 tree, growing in South America, attain the size of twenty- 

 five feet in diameter, and that the African Calabash, or Mon- 

 key-bread, (Adansonia digitata,} is sometimes thirty feet in 

 diameter. But these are but shrubs when compared with the 

 celebrated Chestnut of Mount Etna, so often described by 

 travellers. According to Mr. Swinburne, this tree measures 

 at the ground, 196 feet in circumference, which is nearly 65 

 feet in diameter. The height to which some trees attain, 

 without reference to their diameter, is also truly astonishing. 

 Some of the North American Pines are 230 feet in height, 

 and as straight as though their growth had been directed by 

 the plumb-line of a master-builder. 



From these gigantic trunks, na- 

 ture furnishes every intermediate 

 size of the woody stem, down to 

 that of the Arctic Bramble, (Rubus 

 Arcticus,} an entire shrub of which 

 may be placed in a six ounce vial. 

 Still more diminutive is a kind of 

 Willow, (Salix herbacea,} which 

 Dr. Clarke says is the only tree 

 growing in Spitzbergen. 



Fig. 14, represents this shrub of 

 its full size, with its roots, branches 

 and leaves entire. 



In respect to the longevity of 

 trees, it is known that some spe- 

 cies live from one generation of 

 man to another. Oaks are now 



Fig. 14. 



What plants have woody stems ? In what respects do woody stems 

 diiFer? What is said to he the circumference of the great chestnut oi 

 Mount Etna ? How tall are some of the North American pines said to 

 DC ? What is said of the size of the salix herbacea ? 



