2 55 
% 
Water-conductivity in Sycamore Wood. 
is thus easily identified. Most of the starch, apart from that in the ray 
cells, is stored in these prosenchymatous elements, and wood parenchyma is 
only sparingly developed, rows of shorter, more abundantly pitted, starch- 
bearing cells occurring occasionally near the vessels and among the 
flattened cells of the outer part of the annual ring. The rays, from one 
to six cells wide, may be anything up to forty cells high (1, p. 21 7); where 
ray or wood parenchyma cells come into contact with vessels, the dividing 
walls have numerous half-bordered pits, and these and the living wood 
fibres evidently form one continuous storage system. In the oldest parts of 
SPECIMEN S3. Separate, annual rings. 
the wood examined, five years’, there is abundant starch in the storage cells. 
According to Haberlandt ( 3 , p. 684), Acer is one of the few deciduous trees 
which have no heart-wood ; he states also that, generally, in normal circum- 
stances, only the outermost annual rings of a shoot serve to convey the 
transpiration current, the more internal portions of the sap-wood serving for 
the storage of water and synthetic products. 
The relatively small number of vessels and prevalence of fibres in 
Sycamore wood is mentioned by Strasburger (1, p. 216) ; and he states 
that the comparatively small width of the vessels, averaging about 0-035 mm., 
is remarkable in view of their low proportion. Solereder ( 2 , p. 271) also 
notices the small size of the vessels in Sycamore, and gives the diameter of 
