HOW TO TELL THE WOODS 281 



they are present also but too narrow to be seen with 

 the naked eye. In the conifers there is another pe- 

 culiarity of structure which is helpful in telling one 

 wood from another the size and distribution of "resin 

 ducts." These are spaces between the wood cells into 

 which the resin oozes; their presence, size and number 

 assist in separating one softwood from another. 



For the purpose of classification all the woods found 

 in the United States may be grouped into two classes: 1 



I. Non-porous woods containing the coniferous varie- 

 ties or softwoods. In this class the pores are absent 

 and the limit of the annual ring is marked by the denser 

 and usually darker part grown during the summer. 



II. Porous woods containing the hardwoods. This 

 class of woods contains more wood elements and the 

 growth rings are marked by the presence of large pores 

 in the early spring growth and the more compact 

 arrangement of the late summer growth toward the 

 outside of the tree. A cross section of a chestnut log, 

 for instance, shows very clearly the difference between 

 the spring and summer wood. 



This class of porous woods is further divided into: 

 (a) Ring porous woods, where the pores in the early 

 wood are large and arranged in a ring or band. Chest- 

 nut, oak, hickory and ash belong to this class, (b) 

 Diffuse porous woods. Pores numerous but scattered 

 through the ring. Mahogany is an example of this kind. 

 In some cases the annual ring is made out with diffi- 

 culty. 



iThe New York State College of Forestry at Syracuse has 

 prepared a collection of the most common woods, thirty-one in 

 number, and a bulletin describing this collection, containing a key 

 for their identification. This collection is sent to the citizens of 

 the State upon receipt of $.50 for packing, postage, etc. 



