The Trees of Vermont 201 



of the wood elements. In the hickory it forms numerous, fine, con- 

 centric Hues which are as distinct as the rays. In other woods it may 

 be confined to several rows of cells at the outer limit of the growth 

 ring. 



As a final feature having some value in the identification of certain 

 of the woods, is to be mentioned the so-called "pith flecks". They are 

 common in many of our native woods, appearing as crescent-shaped, 

 discolored patches on the cross-section and as brownish streaks run- 

 ning up and down the stem in longitudinal-section. Pith flecks are 

 not a special kind of tissue, but are tunnels made by the larvae of a 

 two-winged insect which lives in the cambium during the growing 

 season. These pith flecks have been found to occur in only five families 

 of trees in the United States, namely, the willow, birch, rose, maple 

 and linden families. They are by no means constant in their occur- 

 rence ; some stems have numerous pith flecks, while other stems of the 

 same species from the same vicinity do not have them. Taken in con- 

 junction with other characters, however, the presence of pith flecks 

 in considerable numbers may aid in the identification of woods. 



The subject of wood structure is one of absorbing interest to one 

 who will but take a little trouble to go beneath the surface. Facts will 

 be revealed which have hitherto lain hidden because of our usual 

 cursory method of handling wood. Some practise may be necessary 

 at first, a little patience may be needed at times, but success will be 

 the reward of honest effort. In all identification work a very sharp 

 knife is necessary. Surfaces must be cut cleanly and smoothly, keep- 

 ing always in mind that a bruised and broken surface reveals but little 

 of the structure of the wood. Large pieces are not essential, even 

 small cuts along the edge will often suffice. Twigs cut easier than 

 seasoned boards and are frequently as instructive as the more mature 

 wood. Wetting the cut surface will usually make the structural 

 features more prominent. Instructive sections may be made with a 

 very sharp knife or razor, or even with a plane, by cutting very thin 

 pieces and mounting them in water or glycerin between two thin 

 pieces of glass. The sections may even be colored to advantage by 

 soaking them for a time in a dye, thus making certain features more 

 evident. Transparent water colors such as are used in coloring photo- 

 graphs and prints are generally available and will be found to serve 

 as well as the usual laboratory stains. The mounts may be examined 

 with a hand lens by holding them between the eye and the light, or 

 they may be viewed with a compound microscope. If the latter is 



