THE MAGAZINE 
OF 
THE SCHOOL OF AGRICULTURE, 
COLOMBO. 
Added as a Supplement monthly to the "TROPICAL AGRICULTURIST." 
The following pages include the 
Agriculture for March : — 
NUTEITION OF PLANTS. 
By 
C. DrIEBEEG, B.A., F.H.A.S. 
The elements which plants require in order to 
manufacture their food are carbon, hydrogen, oxygen, 
nirtogen, sulphur,— these form the combustible part 
of plants, and are dissipated as gases either alone or 
in combination when the plant is burnt — and po- 
tassium, magnesium, calcium, iron, and phosphorus, 
which form the incombustible part of plants, and are 
left behind as the ash when the plant is burnt. There 
are also nearly always present in the ash. the ele- 
ments sodium, silicon, and ohlorine, with frequently 
magnesium, and it may be other accidental elements. 
This latter group is not considered essential to plant 
life, though it performs useful functions in the economy 
of the plant. From the soil plants obtain by means 
of their roots all the metallic elements ; from the at- 
mosphere they get nearly all their carbon as oar- 
bonic aoid gas, with some water and combined nitrogen. 
The carbonic acid gas derived from the atmosphere is 
decomposed by the chlorophyll cells of the plant 
under the influence of sunlight, the carbon being re- 
tained, and the oxygen — the same volume as was taken 
in in combination — being given off. The carbon, to- 
gether with hydrogen and oxygen in the proportion 
to form water, goes to form starch which is among the 
earliest products formed.. Thus in the process of ela- 
boration the plant takes in carbonic acid gas and 
gives out oxygen : but the process of respiration is the 
same as that of animals, oxygen being inspired and 
oarbonio aoid gas expired. The insoluble starch is 
next converted into soluble glucose by the action of 
diastase a vegetable ferment, and is carried to all parts 
of the plant. The sugar is finally converted into 
cellulose, the material which goeB to form the struo- 
^re of the plant, TVe b»w that ohloropbyll was 
contents of the Magazine of the School of 
necessary for the decomposition of carbonic aoid gas, 
and such plants as do not contain this green colour, 
ing matter do not decompse carbonic aoid gas and 
elaborate starch and its derivatives; such plants are 
the true parasites, the saprophytes and the insectivorous 
plants, which will be dealt with afterwards. 
The formation of albuminoids is not yet fully un- 
derstood, but they are supposed to be built up out 
of carbo-hydrates and the nitrogenous substances in 
the sap. The albuminoids require the elements carbon, 
hydrogen, nitrogen, and sulphur for their construction. 
The fatty matter is derived either from the carbo- 
hydrates or from the splitting up of the albuminoid 
oompounds; and the vegetable acids by the oxidation 
most likely of the carbo-hydrates. 
Experiments in water-culture in Germany, — by which 
plants are artificially supplied with solutions of salts in 
distilled water — prove that plants oan get all the neces 
sary elements of food in a mixture either of calcium 
nitrate with acid pottassium phosphate, potassium 
nitrate, magnesium sulphate, ferrous phosphate, and 
sodium chloride; or calcium nitrate with ammonium 
nitrate, potassium sulphate, magnesium phosphate, and 
ferrous ohloride. 
The process of respiration in plants is best observable 
at night when no manufacturing of starch goes on as 
there is no sunlight present. 
There is thus a mutual dependence of the animal and 
vegetable kingdoms on each other : for the carbonic 
acid gas which is hurtful in any quantity to animal life, 
is utilized in the prooess of elaboratiou by plants, 
which in return supply oxygen for the support of 
animal life : while man helps in the supply of car- 
bonic acid gas which constitutes so important a factor 
in the vegetable economy, 
