OLEORESIN PRODUCTION. 5 



Longleaf pine as found in the southern United States of America 

 is the species chiefly discussed and illustrated in the following pages 

 as the typical producer of American naval stores. Botanically, it is 

 classed in the division of the Spermatophyta, the subdivision of the 

 Gymnospermae, the order Coniferales, and family Pinaceae. The 

 structure of the wood, the principal subject of this research, as seen 

 with the aid of the microscope in an end view or cross section made 

 from a normal unturpentined specimen, is shown in Plates II, V, and 

 VI. The yield of oleoresin, obtained when a tree is wounded, comes 

 from the cells of the aggregates GP, Plate II, figures 3, 4, 5, and 

 elsewhere. 



CAMBIUM. 



The cells of the wood and bark of the pine are formed by the 

 division and differentiation of the cells of the cambium layer, which 

 is situated between the bark and the wood (C, PL II, fig. 1). This 

 layer is made up of thin- walled cells, which retain their power to 

 divide and thus produce the new cells composing the yearly rings of 

 bark and wood, respectively. 11 



ANNUAL RINGS. 



The layer of new wood formed each year on the outside of the 

 woody core of a tree is known as an annual ring (AR, PI. II, figs. 1, 

 2, 3, and 5.) In the pines in question it is conspicuously differen- 

 tiated into two portions. The spring wood (SP) has thin- walled 

 cells and large cavities, and forms early in the growing season. The 

 summer wood {SM) has denser cell walls, and though it may begin 

 to form as early as June, it generally develops in July, or, at the 

 latest. August. The width of the annual ring and the amount and 

 density of the summer wood formed are markedly influenced hj tur- 

 pentining, and serve as indicators of the effects of the various 

 methods used. 



SAPWOOD AND HEARTWOOD. 



A varying number of the outermost annual rings of wood make 

 up the sapwood. This is usually lighter in color than the heartwood, 

 OX central portion of the tree. The water solutions of the sap cir- 

 culate through the sapwood, and it is in this region that the oleoresin 

 exudes from certain cells (parenchyma) which are characteristically 

 active. Each year a portion of the inner sapwood ceases to function 

 and becomes dead heartwood; as a result the thickness of heartwood 

 increases writh the tree's age, but that of the sapwood remains, with 

 relatively small variations, approximately the same. The, walls of 



" it. Ii the cambium tbal tean when the wood Ih separated from the i>:iri< cylinder in 

 making ■■> willow wbl 



ST 10 1" 22 2 



