BEAJq-CHES. 7 



year to year. Between each year's growth there is gene- 

 rally a line, in some cases more conspicuous than in 

 others, that marks off the formation of each year, so 

 that we are able to reckon the ages of trees with great , 

 accuracy by these rings. "When it happens that a tree,*' 

 from certain circumstances, makes more growth one season 

 than another, we find the ring of that season larger. The 

 new wood is always formed between the inner bark and 

 the last layer of wood, so that one layer is laid upon, and 

 outside of another, and the bark is continually pressed , 

 outwards. 



The new layers of bark are also formed at the same 

 place, or within the previous one. From this mode of 

 growth, it results that each layer of wood is more deeply 

 imbedded as others ar^ formed on the top of it ; and 

 each layer of bark is pressed outwards as others are 

 formed within it. In some cases, as in the cherry, for 

 example, the bark is so tough as not always to yield to 

 the general expansion of the tree, and slitting is resorted 

 to for the purpose of preventing an unnatural rupture, 

 which would eventually take place by the continued 

 pressure of growth from within. 



Section 3. — ^Braitches. 



Branches are the divisions of the stem, and have an 

 organization precisely similar : they are designated as, 



1st. Main Branches {F^ fig. 1) ; those that are directly 

 connected with the stem or trunk. In pyramidal trees, 

 they are called lateral branches. The branches of different 

 species and varieties of fruit trees, difter much in their 

 habits of growth ; and it is highly important to the planter to 

 consider these peculiarities, because certain habits of growth 

 are better adapted to particular circumstances than others. 

 Thus we have erect branches (fig. 3), which produce trees 



