Trees — The Character, Struchire, Sec. 45 



parenchyma), frequently fade out before completely encircling 

 the log, or they anastomose ; this does not occur with annual 

 rings, however eccentric and close they may be. Sometimes 

 these bands or lines consist of whitish resin-containing pores, 

 commonly found in timbers belonging to the Dipterocarpaceoe. 

 Timbers Avith these "false rings" as they are usually called, 

 frequently have no distinguishable annual rings, and this is 

 generally attributed to the season of growth not being sufficiently 

 separated by periods of rest to form shai-ply marked zones of 

 Avood. Even in these woods, a cessation of growth such as caused 

 by drought followed by a period of renewed activity may occasion 

 the formation of rings which are perhaps more appropriately 

 called " season " rings. 



Annual rings show the age of a given section. At the butt 

 of a trunk, if it includes the first year's growth, it will give the 

 age of the tree. The tree may be 40 years old at the base, 25ft. 

 up the trunk may be only 20 years old. The rings may also 

 serve as records at different ages of the periods of suppression or 

 activity. 



The number of rings, as an indication of age, is not always 

 infallible. It occasionally happens in trees that two rings are 

 produced in one gi owing season. The growth of wood is the 

 result of the physiological activity of the leaves, as they are the 

 workshops where the food is manufactured, and if the tree is 

 defoliated, for example, by frost in May, or by insects as some- 

 times happens to the Oak in July, another crop of leaves from 

 dormant buds will frequently appear, resulting in the formation of 

 a second ring. 



Heartwood and Sapwood. — If we examine the cross cut 

 end of any old oak stump, after the trunk has been felled, we 

 see at once that it is clearly separated into two regions, — a darker, 

 drier central portion surrounded by a pale moist softer portion. 

 The deep coloured central part is called heartwood {duramen) 

 and the outer part is known as sapwood {alburnum) sometimes 

 referred to as "heart" and "sap" respectively. The heartwood 

 is dead, and is usually the warehouse for storing colouring matter 



