264 Holmes. — Observations on the Anatomy of Ash-wood. 
Thus on the whole Hazel-wood has a greater number of water-conducting 
elements per square millimetre than Ash-wood, which more than compen- 
sates for the smaller diameter of these elements and their greater resistance 
to the flow of water on this account. The relatively low specific con- 
ductivity of Ash-wood must be attributed to its relative poverty in vessels. 
It is to be understood that these observations apply to wood of the first 
year only, and that a still greater range of variation might, and probably 
would, be found for some of the characters — for instance, in those forming 
the basis of curve E — by examining a larger number of examples ; but I am 
inclined to think that the general range for specific conductivity would not 
be altered materially, and that the relation between Ash- and Hazel-wood 
in this respect would remain as indicated above. 
Summary. 
The results obtained from a quantitative investigation of the constitu- 
tion of Ash-wood in young shoots, with special reference to vessel content, 
have been discussed, and compared with similar data previously obtained 
for Hazel-wood. It is shown that on the whole there is a fall in absolute 
water-conductivity and a rise in specific conductivity from the base of 
a shoot to its apex, in both kinds of wood examined, and that, in general, 
the figures for specific conductivity are lower in Ash than in Hazel. In the 
latter the water-conducting elements are more numerous than in the former, 
though on the whole they are not so wide. 
My thanks are due to Professor Parmer, of the Imperial College, 
South Kensington, for his suggestion of this work and his help in carrying 
it out, and to Professor Potter, of Armstrong College, Newcastle-on-Tyne, 
where part of the work was undertaken. 
