THE RESINOUS EXUDATION OF ROSEWOOD. 239 
fibres are commonly septate with very thin dividing par- 
titions, and are often saw-edged at the ends. Scattered 
throughout the tissues are the rows of elongated xylem 
parenchyma in which the oleo-resin also occurs, the cells 
measuring up to 0°1 m.m. in length, and 0°04 m.m. in 
diameter. In radial section (Figure 4) the medullary rays 
are found to be homogeneous. 
Summary.—A_ resinous exudation commonly known as 
“sweating’’ occurs in the timber of Rosewood, Dysoxylon 
Fraseranum destroying the polish. 
A microscopical examination showed the presence oi 
small oil globules in certain cells of the woody tissues, e.g., 
the elongated xylem parenchyma and alsoin the medullary 
rays, not only in mature heart-wood, but also in the sap- 
wood of young branches. | 
Steam distillation of shavings gave a bluish coloured, 
rather unpleasant smelling, viscous oil, with a yield of 3°4°> 
on air dry wood. 
Attempts to cause “‘sweating’’ to take place by subject- 
ing the timber to varying conditions of heat and moisture 
were as a rule not successful. 
Pieces of Rosewood steamed or sponged with alcohol 
apparently retain the polish much longer than untreated 
wood. 
Sweating is probably due, in many cases, to the use of 
unseasoned timber, or to the polishing of wood which has 
recently been given a fresh surface, i7.e., oxidation of the 
oleo-resin in the surface cells has not taken place. 
In conclusion I wish to thank Prof. A. A. Lawson, D.Sc., 
and Mr. G. Hooper, F.T.c., for the interest and helpful 
criticism given in this work. Iam also indebted to Mr. 
