IN CEYLON. 
21 
Diospyros genus. The leaf production is apparently not of 
such a nature as to severely tax the resources of the plant, 
and its occurrence is probably to be correlated with indivi¬ 
dual requirements rather than with climatic conditions. 
This can only obtain in the vegetation of the tropics 
where the temperature and rainfall are relatively equable 
throughout the year. 
IV.—ANATOMY, TIMBER , Ac. 
Stem .—In the genus Diospyros the phellogen is often 
said to be of sub-epidermal origin, and this is considered by 
Parmentier and Solereder to be of taxonomic importance, 
the former using this as one of the main characters in his 
proposed grouping of the genera. The phellogen, however, 
actually arises either immediately beneath the epidermis or 
from the pericycle, the latter origin being conspicuous in the 
primary axis or hypocotyl of the seedlings. 
The sclerotic or stone cells of the cortex are conspicuous 
in D. Ebenum, and the various stages of their formation and 
degeneration are shown. (See pi. XIX., figs. 1-4) ; they are 
relatively short, thick walled, and well pitted ; finally they 
lose their definite outline and form hyaline masses of tissue, 
which do not respond to the commoner staining reagents. 
In longitudinal section they are seen to be surrounded with 
parenchyma and long sclerenchymatous fibres. The phloem 
and cambium are of the ordinary type, and we may proceed 
to deal with the anatomy of the secondary xylem. 
The observations of Molisch, Möller, Solereder, and 
Parmentier, already referred to, all agree as to the regular 
composition of the secondary xylem, the scarcity of tracheids, 
and the distribution of the elements. 
Molisch obtained his sections of the hard brittle ebony by 
the method of Wiesner, which is briefly as follows : A thin 
slip of ebony, 2 to 3 cm. square, is cut by a fret-saw and 
fastened by means of sealing wax to a cork ; both sides of 
the section are then polished on a smooth rotating wheel, 
