Chap. I.] BY THE SURFACE OF THE ROOTS. 
33 
sequently, the extremities of the roots, with 
their supposed spongioles, are very far removed 
from the supposed drip from the outside of the 
head of a tree. 
But in reference to this drip round the out¬ 
side of the heads of trees, the phenomenon may 
be seen from umbrellas and roofs. But trees are 
neither umbrellas nor roofs, as those who take 
shelter under them will find. As long as their 
leaves and branches can absorb or hold on their 
surface the mass which falls, they will afford 
shelter. But after that the rain will not trickle 
outside the circle, but perpendicularly through 
every part of the head. Thus much for what 
takes place when the trees are in leaf. For six 
or seven months, however, they are without 
leaves. And in the spring they are without 
them, at the particular time when the great 
upward supply is required for the very form¬ 
ation of the leafy canopy which is supposed to 
supply the supposed circle of spongioles. This The head robs 
leafy canopy, far from supplying the circle nttie rain^but; 
around it and below it with rain , robs it of as *> a y s this ?y 
condensation. 
much as is absorbed by the leaves, or as is eva¬ 
porated from their surface. But this robbery 
is much more than compensated by the conden¬ 
sation which takes place whenever the atmo- 
D 
