50 



scorch bo kill it. It is common to see such a tree, after 

 fire has killed all its smaller branches and burnt the bark 

 black, break out into bunches of fresh vegetation all along 

 the stem 



If you cut a large piece of bark right down to the wood 

 it can easily be torn away ; then both the wood and bark 

 will be covered with a colourless slimy substance. This 

 appears in such a condition because its structure has been 

 destroyed in pulling off the piece of bark. In its natural 

 condition in consists of a few layers of very delicate cells 

 lying between bark and wood. These cells are in a con- 

 dition of active growth, constantly forming layers of bark 

 cells or fibres on the outside and wood on the inner side. 

 This layer of delicate cells, which is called the cambium, is 

 responsible for forming the whole of the bark and wood. 

 It may go on with its work all the year round, or may 

 rest during the cold of the winter. Its activity may also be 

 much reduced when lack of rain causes a dryness of soil. 

 Trees growing in places where there is a marked but con- 

 stant change of summer heat and winter cold, but never 

 irregular periods of soil dryness, will form regular yearly 

 rings of softer spring wood and denser autumn wood. 

 This is very well marked in trees that shed their leaves 

 in winter, in Pines, and in Gums growing at a consider- 

 able altitude. A Eucalypt placed at a low elevation grows 

 all the year round, though it slows down somewhat in the 

 winter ; but if in summer its water-supply is reduced 

 beyond its maximum requirement by a period of drought, 

 development will be checked and the forming wood will 

 be thin and hard, but will again be looser on return of 

 moisture. This is why in Gum timber the rings are not 

 always to be relied upon as indicating the age of the tree, 

 and has given rise to the statement that our trees form 

 two layers of wood per annum. The same tree may lay 

 down one to three layers according to the condition of the 

 season . 



We have in Tasmania only one native, a Beech, of our 

 westerly mountains, that sheds its leaves in winter; all 

 the rest are evergreens. A tree growing at a high altitude, 

 where there is inefficient or no sunlight during some 

 months, will benefit by shedding its foliage; also, trees 

 growing in districts subject to regular periods of great 

 summer drought may benefit in the same way. But with 

 us neither condition obtains. We can only think our 

 deciduous Beech an immigrant from a more southern land* 

 that has not the ability to change its character. 



