544 Rivett. — The Anatomy of Rhododendi' on ponticum, L,, and of 
that the friction in vessels of small lumina is greater than that in large, and 
that this will affect the conductivity in the sense that, area for area, it will 
be lower in vessels which are narrow and numerous than it will be in those 
which are fewer and wider. 
Diagram XIII. Internodes numbered from base to apex. (Scale, 5 internodes = 1 cm.) 
In the holly the D curve is noticeable because it is hardly affected by 
the yearly joints as are the curves B, C, and E. The highest figures are 
found at the bases of the oldest shoots, and they become lower in the 
passage through successive years to the apex. This is due to the fact 
that the vessels in the outer rings of wood are, on an average, slightly 
