Here - The Alfred Russel Wallace Website

14 THE WORLD OF LIFE CHAP
will be referred to later, are manifestly due to that "
struggle
for existence " which is one of the great factors of evolution
through " survival of the fittest."
A Lincolnshire clergyman (Rev. E. Adrian Woodruffe-
Peacock of Cadney) has long studied the distribution of
plants in a very minute and interesting manner, more
especially in his own parish, but very extensively over the
whole county. His more exact method is to divide up a
field into squares of about 16 feet each way with pegs, and
then to note on special forms or note-books (i) a list of the
species found in each square, and (2) the frequency (or
proportion) of the occurrence of each species. From these
the frequency over the whole field can be estimated, and
the botanical peculiarities of various fields very accurately
determined. By comparing the detailed flora of each field
with its surface-geology, aspect, altitude, degree of moisture
or aridity, etc., a very accurate conclusion as to the likes
and dislikes of particular plants may be arrived at.
As an example of the detailed treatment of a rather
uncommon yet widely distributed plant, he has sent me a
copy of his paper on the Black Horehound (Ballota nigra),
a species not uncommon over much of Central Europe, but
scattered over Central and Southern Britain only in a few
favourable localities. In Lincolnshire it is found all over
the county in suitable spots, but prefers a warm, open, and
notes of its
limy soil, as shown by 150 records giving
occurrence. The general results of the inquiry are thus
given :
" When the sheets of notes are analysed the following points come
out. It is a hedge and ditch-side species, but it seems to prefer a
bank to the flat in the proportion of 10 to i ; the sunny bank to
the shady side of a road running east and west in nearly the same
proportion. On sandy soils it seems to get away from the villages
to a greater
explain
distance than on clays, but perhaps the rabbit may
this. It extends from Cadney village along hedge and
ditch banks on roadsides as far as the Sandy Glacial Gravel extends
in any direction. It is found in bushy ground, in old quarries and
gravel pits, and on the decaying mud-capping of limestone walls.
It is exterminated by stock in pasture, unless it is protected by the
stinging-nettle or by the fouling of the ground by rabbits. It is
apparently never found in meadows. It is even sometimes eaten