TREES AND WOODS 



not usually find these rings. By counting them 

 it is often possible to get some idea of the age 

 of the tree ; but the rings themselves vary in 

 thickness, according to the age of the tree, their 

 distance from the centre of the trunk, and the 

 character of the season in which they were 

 formed. We can also best study the growth of 

 the bark when a tree has been felled, and shall 

 notice among other things that it is often the 

 home of many beetles and insects. Some of 

 these are very destructive to timber, and are 

 especially apt to breed in rotten and decaying 

 wood. We shall therefore find that the bark is 

 usually stripped off the trees before they have 

 been long cut down, and it is wise to take 

 away the old tree stumps lest they should be- 

 come centres of insect-life which would spread 

 afterwards throughout the forest. The birds 

 that we see in woods are nearly always insect- 

 eaters, and often have beaks which seem to be 

 made on purpose to pick the beetles out of the 

 bark ; in this way they help to keep the trees 

 in good condition, and should be left in peace 

 and encouraged to stay about 



There is a curious thing we may perhaps 

 notice either in trees when they are growing or 

 in timber after it is cut down. If we look 

 attentively at the bark of certain trees, we shall 

 see that it does not appear to be straight but 



frows round the tree, sometimes to the right 

 and and sometimes to the left, in corkscrew 



