160 
operations, and acquired for the purpose of dis- 
covery. 
Plants being possessed of no locomotive powers 
can grow only in places where they are supplied 
with food ; and the soil is necessary to their 
existence, both as affording them nourishment 
and enabling them to fix themselves in such a man- 
ner as to obey those mechanical laws by which 
their radicles are kept below the surface, and their 
leaves exposed to the free atmosphere. As the 
systems of roots, branches, and leaves are very 
different in different vegetables, so they flourish 
most in different soils : the plants that have bul- 
bous roots require a looser and a lighter soil than 
such as have fibrous roots ; and the plants pos- 
sessing only short fibrous radicles demand a firmer 
soil than such as have tap roots, or extensive late- 
ral roots. 
A good turnip soil from Holkham, Norfolk, 
afforded me 8 parts out of 9 siliceous sand \ and 
the finely divided matter consisted 
Of carbonate of lime - - 63 
— - silica - - - 15 
— alumina - - - 11 
— oxide of iron - 3 
. — vegetable and saline matter - 5 
— moisture - - 3 
I found the soil taken from a field at Sheffield- 
Place in Sussex, remarkable for producing flourish- 
ing oaks, to consist of six parts of sand, and one 
part of clay and finely divided matter. And one 
hundred parts of the entire soil submitted to ana- 
lysis produced 
