A Study in the Anatomy of Hazel-wood with 
Reference to Conductivity of Water. 
BY 
M. G. HOLMES, B.Sc. 
With two Figures and eight Graphs in the Text. 
T HE work described in this paper was carried out under the direction of 
Professor Farmer at the Imperial College, the aim being to find an 
anatomical basis for variations in the conducting power of wood for water. 
Professor Farmer has shown experimentally, in his recently published 
papers, 1 that the wood in different regions of the same shoot may vary con¬ 
siderably in specific conductivity; that is, in the conducting efficiency 
calculated for equal areas in transverse section and equal lengths. The total 
conducting power of the wood at any one position in the shoot depends 
partly upon the area of the wood in transverse section, but is influenced also 
by the specific efficiency, or quality, of the wood. In one shoot the total 
amount of water to be transmitted through the wood decreases from near 
the base upwards; if the wood were equally efficient as a water-conducting 
medium in all parts, the decrease in the area of the transverse section would 
be a measure of the decrease in conductivity. But the wood is by no means 
equally efficient as regards this function; and therefore comparison of the 
amount of wood in transverse section is not sufficient to explain differences 
in the total amount of water passed through in a given time: a further 
explanation must be sought in differences in constitution. Thus variation 
in specific conductivity must be related to variation in the number, size, 
character, and distribution of those elements in the wood through which 
the water passes. 
Considered as a whole the wood has more than one function. Through 
the tracheae or vessels, and the tracheides, it conducts water; but these 
water-conducting elements are associated with woody fibres having a 
mechanical function only, and also with living cells. During autumn and 
winter the latter are filled with starch, and they may be classed together as 
storage tissue. I shall not enter here into the question of how far the living 
cells, help in the water-conducting process: for the purpose of comparing 
water-conducting efficiency I have taken into consideration only the character 
1 J. B. Farmer: On the Quantitative Differences in the Water-Conductivity of the Wood in 
Trees and Shrubs, Parts I and II. Proc. Roy. B. Soc., vol. xc., 1918. 
[Annals of Botany, Vol. XXXII. No. CXXVIII. October, 1918.] 
