IN CEYLON. 
53 
dark reddish brown in colour, which can be extracted from 
the original ebony dust with alcohol and amounts to 3’58 
per cent, of the dust. 
The black colouring material therefore contains two gums, 
one resin, and an insoluble residue composed mainly of 
carbon. 
It has been asserted that the colouring materials arise by 
chemical change of the inner layer of the elements in which 
they occur, and even Molisch believed that the reputed thinness 
of the walls of some vessels was due to part of the material 
having been so modified. My own observations do not 
confirm this theory, though I have noticed a certain amount 
of swelling when sections of the fresh wood are placed in 
water. This is probably due to the absorption of water by 
the thin layer of gum which forms a lining to the tracheal 
elements, and which occurs in the yellow or white sapwood 
of ebony-bearing species. 
From an examination of longitudinal sections of the 
sapwood and heartwood of our species I have concluded that 
the greater part, if not the whole, of the coloured materials 
filling the lumina of the elements is derived from the 
materials accumulated in the parenchymatous system of the 
secondary wood. Usually the discolouring substances make 
their first appearance in the cells of the medullary ray or 
wood parenchyma, then in the tracheal elements, and lastly 
in the fibres. 
The parenchymatous elements of the sapwood are invari¬ 
ably packed with starch grains, tannin, and calcium oxalate. 
The starch grains gradually lose their regular outline and a 
fine granular texture becomes obvious, together with a change 
in colour. Finally, globules suggestive of a resin or gum 
appear in the parenchyma cells, and as these increase a deepen¬ 
ing of tint from yellow to brown occurs. It would therefore 
appear that by a series of chemical changes the contents 
of these elements gradually disintegrate, and the resulting 
compounds are in the form of globules of coloured material. 
It must, however, be remembered that starch is a stable 
