fi WRIGHT : THE GENUS DlOSPYROS 
the axis was more thoroughly dealt with, and a theory was 
set forth explaining the enhanced durability of ebony as a 
consequence of the walls of the elements being impregnated 
with a colouring substance of unknown chemical constitu¬ 
tion. 
A much more instructive paper was then issued by 
Molisch,* who prepared his sections by the method of 
Wiesner. Molisch described the anatomy of the stem of 
two of our species, D. Ebenum, Koen., and D. sylvatica, 
together with three others, and a species from each of the 
genera Maba, Euclea, and Royena. He attempted to combine 
the facts of internal construction with external morphology, 
believing with Radlkofer that this would provide the best 
basis for a systematic grouping of the plants. He also laid 
stress on the striking anatomical resemblances of the species 
he examined, and endeavoured to discover whether the 
reason of the high technical value of the ebony woods lay 
in the anatomical construction or in the chemical changes 
going on within the tissues. 
In connection with the colouring matter of the timbers, 
he believed that the initial deposits were true gums, and 
that the suspected resin was a product of a slow process of 
humification going on within the elements. He further 
endeavoured to show that seasonal rings of growth were 
found in the secondary xylem of trees of D. Yirginiana, A., 
which had been grown in Europe, whereas those grown 
in the tropics showed no such histological differentiation. 
The various points raised by Molisch will be subsequently 
discussed under their respective sections in the present 
contribution. 
Hartigf has given an account of the timber of several 
species, and has discussed the views of Moeller and Molisch 
as to the nature of the colouring substance in ebony. He 
* H. Molisch, Vergleichende Anat. des Holzes der Ebenaceen und ihrer 
Verwandten. Sitz. Akad. Wiss. zu Wien, Bd. 80, Abth. 1, 1879. 
t Hartig, Bot. Ztg., p. 108,1859, and also Lehrbuch für Förster, I. Theil, 
p. 256, 1861. 
