268 Holmes . — Water-conductivity in Sycamore Wood. 
Note. 
Miss Rivett. has been so good as to let me see a copy of her paper (8) 
on Rhododendron and Holly, before its publication. On p. 549 she draws 
attention to the lack of consistency between the deciduous and evergreen 
woods investigated, in comparing the data for C with Professor Farmer’s 
figures for specific conductivity. The correction mentioned above does not 
increase the values of C for Hazel and Ash sufficiently to bring them into 
a relation with the corresponding specific conductivity values, similar to that 
which obtains in the case of Rhododendron and Holly. This will be 
seen from the following table giving mean average values in all cases : 
Plant. 
C. 
Spec . cond . 
Rhododendron 
23 - 8 % 
16 
Holly 
8-o% 
9 
Hazel 
n- 7 % 
3 i 
Ash 
5*5 % 
14. 
Sycamore 
11 ' 4 % 
35 
. ... S 
It appears, therefore, that the anomaly must be due to the incidence 
of longitudinal characters. Professor Farmer has pointed out (5, p. 249) the 
effect, in lowering the specific conductivity, of the short vessels which are 
characteristic of the evergreens. Miss Rivett concludes that the narrower and 
probably shorter vessels in the evergreens offer more resistance to the 
passage of water, so that for them a comparatively high value for c is to be 
expected. In this sense a particularly low value for C should be found 
in the case of Ash, while that for Sycamore should be somewhat lower 
than that for Hazel. 
I am glad to take this opportunity of thanking Professor Farmer Ij 
for the provision of material and for his help during the progress of the 
work. 
Literature cited. 
I 
1 . Strasburger: Ueber den Bau und die Verrichtungen der Leitungsbahnen in den Pflanzen. , 
1891. 
2. Solereder : Systematische Anatomie der Dicotyledonen. 1899. 
3 . Haberlandt : Physiological Plant Anatomy ; translation by Drummond from edition of 1909. j 
1914. 
4 . Salisbury, E. J. : The Determining Factors in Petiolar Structure. New Phyt., vol. xii, 1913. 
5 . Farmer, J. B. : On the Quantitative Differences in the Water-conductivity of the Wood in Trees 
and Shrubs, Parts I and II. Proc. Roy. Soc., B., vol. xc, 1918. 
6. Holmes, M. G. : A Study in the Anatomy of Hazel-wood with reference to Conductivity of 
Water. Ann. Bot., vol. xxxii, 1918. 
7 . — l : Observations on the Anatomy of Ash-wood with reference to Water-con- 
ductivity. Ibid., vol. xxxiii, 1919. 
8. Rivett, M. F. : The Anatomy of Rhododendron ponticum , L., and of Ilex Aquifolium , L., in 
reference to Specific Conductivity. Ibid., vol. xxxiv, 1920. 
