Ilex Aquifolium , L., in Reference to Specific Conductivity . 537 
elements at these points (see Curve E). The slight variations in the form 
of the curve in different shoots and different years are due to the varying 
number of internodes, to the rate of decrease in the wood-area, and to the 
changes in size and number of the water-conducting elements. In Shoot F 
the curve is nearly flat at the beginnings of the yearly segments and 
descends at their apices : it terminates nearly flat owing to the abortion 
of the apex. In Shoot G the curve is very similar, but there is a slight 
Diagram VI. Internodes numbered from base to apex. (Scale, 5 internodes = r cm.) 
departure from the general descent in the middle of the three-year-old 
segment, due to the large number of water-conducting elements at that 
region. In Shoot H the general descent is very gradual, because the stem 
tapers very gently and there is no great variation in the cross-area of the 
water-conducting elements throughout the very long stem, but the yearly 
segments are well marked. In Shoot K the yearly segments are again 
well marked, and, though they are similar in form, the actual figures vary 
considerably. In the four-year-old segment the wood-area is decreasing 
