14 THE WORLD OF LIFE 



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 

 limy soil, as shown by 150 records giving notes of its 

 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 1 ; 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 distance than on clays, but perhaps the rabbit may 

 explain 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 



