the Age of Trees from the number of Rings. 451 



sharp line of demarcation, visible to the naked eye, of the 

 zones of wood in so many of our forest trees. 



3. This line of demarcation is, in many species, accentu- 

 ated by an aggregation of the vessels into a circle close to 

 the inner edge of the spring wood ; but in other species this 

 character is wanting, as the vessels are distributed more 

 equally, often in successive circles, through the zone. The 

 cut mouths of the vessels are generally quite visible to the 

 naked eye. 



Character of the Rings in the Specimens to the Naked Eye. 



Rohinia pseudoacacia. — On the dark smoothened surface of 

 the block, ten thin whitish circles sharply mark out eleven 

 zones of wood, corresponding with the known age of the 

 specimen. These circles are caused by the presence of the 

 second and third characteristics noted above. A large 

 number of very distinct concentric rings are also caused by 

 a tendency to a circular arrangement of the vessels through- 

 out the zones, but there is no risk of these being mistaken 

 for annual zones. 



Melia azedarach. — On the smoothened, reddish-brown 

 surface, nine whitish concentric lines, at tolerably regular 

 intervals, are clearly marked, besides eight others confined 

 to the inner radius of half an inch. Judged by a British 

 standard, therefore, we should pronounce this tree to be 

 eighteen years old, the earlier eight years' growth having 

 been very slow, as we often see. But the actual age of the 

 tree is only eleven years. Besides these solid-looking circles, 

 there are upwards of 100 very distinct quasi-circles, formed 

 of innumerable vessels with whitish walls. 



Acacia melanoxylon. — The smoothened surface shows a 

 series of concentric waves, alternately whitish and brownish, 

 very numerous, and with no sharp lines of demarcation. At 

 intervals, two or three of the brownish waves are broader 

 and darker, and thus vaguely define eight zones of wood, 

 corresponding in number to the years of age of the tree. 

 The two inner of these vague boundaries are of a wavy 

 blackish-brown all over. The vessels are small, numerous, 

 and not in rows. 



Acacia moUissima. — The smooth surface shows a large 



