699 



CHAPTER IV. 



PROPERTIES, HARVESTING, SELLING AND 

 DISPOSAL OF RESIN. 



SECTION I. ANATOMY.* 



TURPENTINE is elaborated naturally either in intercellular 

 spaces surrounded by cells, or in certain cells. A distinction 

 therefore is made between resin-ducts and resin-cells. The 

 latter are parenchymatous cells in which turpentine occurs in 

 drops, so that a cell contains more turpentine as it becomes 

 older ; as soon as the plasma leaves the cell, no more turpen- 

 tine is formed in it. The plasma leaves the cells, when the 

 sapwood, which contains them, is converted into heartwood, 

 or when the bark, in which also they occur, is cut off from 

 living cortex by the formation of layers of cork, or of rhiti- 

 dome. All the transverse parenchyma in the medullary rays, 

 both in the wood and cortex of conifers, contain resin-cells ; 

 in the longitudinal parenchyma, only the resin-cells that 

 surround the resin-ducts contain turpentine ; so do frequently 

 the last cells of the annual zones of wood in silver-iirs and 

 tsugas. In the cortex, besides the cells of the medullary rays, 

 the phelloderm, hypoderm and the gate-cells of stomata, 

 contain turpentine. 



Resin-ducts are formed only at the time of the formation of 

 the plant-part, which contains them ; there is not, in conifers, 

 any subsequent formation of intercellular spaces by the dis- 

 solution of tissues. The partition of the walls of a cell in 

 order to form a duct and the flow of turpentine into the duct 

 are simultaneous. The diameter of a duct increases by the 

 division of the cells that surround it, and as each new cell is 

 formed, more turpentine flows into the duct. In the wood, 

 there is no increase in the breadth of a duct after the year of 



* H. Mayr, " Die Secretionsorgaiie der Fichte und Larche." Bot. Zentralbl. 

 IKS:,. Also, " Das Harz der Nadelholzer." Berlin, IS'.M. 



