Water -conductivity in Sycamore Wood . 265 
of each growing season. For instance, the repetitions of Curve A in Figs. 2, 
8, 10, and 13 give a sufficiently clear idea of the general effect of the yearly 
additions to the’ area of the wood. The curves are fairly smooth, apart 
from the local rises at the ends of segments, as noticed above. Turning to 
the statistics for the water-conducting elements as given in Figs. 3, 7, and 
10, we find that the curves for D become smoother and flatter, as the 
influence of the first-yeai -^ood is less felt. On plotting the total numbers 
of these elements present in the whole of the wood, there is produced 
for each plant a series of descending curves, F, in which the most con- 
spicuous irregularities are local maxima at the ends of the segments. In 
some cases these are sufficient to eliminate the effect of the maxima at the 
beginnings of the segments, which appear in Curves F for the annual rings 
taken separately, as pointed out in Fig. 4 ; examination of Figs. 3 and 10 
will serve to illustrate this point. At the end internodes, naturally, F includes 
many very small elements, as is indicated by the local minima in Curves E, 
Figs. 3, 7, and 10; consequently in' Curves B, Figs. 2, 6, and 9, which give 
the result of taking these two factors together, there is less irregularity. If 
Curve B be taken to express as far as possible the absolute conductivity of 
the wood as a whole, its general slope downwards from base to apex of the 
plant may be considered with reference to the number of leaves borne 
