5 3 6 Rivett . — The Anatomy of Rhododendron ponticum, L,, and of 
which the mass of supporting fibres is limited to the extreme base, and 
in which there is a sudden increase of vessels in the first elongated inter- 
nodes, the curve tends to rise slightly at first, because the increase in the 
total cross-area of the vessels more than makes up for the slight decrease 
in area of the wood. This preliminary rise is most marked in Shoots E4, 
Ea, Di, and Ai. Similarly, at the beginning of the foliar region, where 
there is a slight increase in the size of the vessels, we may have either 
Diagram V. Internodes numbered from base to apex. (Scale, 5 internodes = 1 cm.) 
a flattening or slight ascent of the curve, because here the tapering of the 
stem is slight and any increase in the actual area of the vessels becomes 
noticeable in the total area in the section. The range of actual figures 
is from 5-9 sq. mm. in B 1 to 1-4 sq. mm. in A3. In the shoots of holly 
the general descent of the curve throughout the length of the twig is 
interrupted by more sudden descents at the yearly joints, which begin at 
the apex of one year and extend into the lowest internodes of the next. 
These sudden descents are due to a decrease in number of water-conducting 
