Chap. I.] BY THE SURFACE OF THE ROOTS. 
31 
sun. All grew. By midsummer, and after that, 
the thermometer frequently stood at 84° in the 
shade, and 111 0 in the sun, on the wall under 
which Nos. 1, 2., and 4. were growing. Not a 
leaf of either flagged. There were by this time 
flowers on the tops of the stalks in all three ex¬ 
periments : and in the autumn all bore seed most 
profusely, much of which ripened. 
First comes the unsound datum, then follows 
the unsound theory. Koget remarks, in reference 
to roots, that “ as a constant relation is preserved 
between their lateral extension and the horizontal 
spreading of the branches, the greater part of the 
rain which falls upon the tree is made to drop 
from the leaves at the exact distance from the 
trunk where, after it has soaked through the earth, 
it will be received by the extremities of the roots, 
and readily sucked in by the spongioles.” This is 
the notion of indoor bookish theorists. I forget 
who first made the observation, but, as it is re¬ 
peated by almost all writers on vegetable phy¬ 
siology, it deserves notice. Both the facts here 
supposed may be considered as vulgar errors. 
That is, in general , the horizontal extension of 
the roots will be found far to exceed that of the 
branches; and so far from its being true that 
less water falls under the head of a tree than out- 
That branches 
are the same 
length as roots 
a fallacy, and 
that the ends of 
branches drop 
on to the ends of 
roots a fallacy. 
Branches 
shorter than 
roots, and the 
drop is through 
them, not out¬ 
side them. 
