20 HINTS ON SOILS AND FERTILIZERS 
of sunlight, which explains why sunlight is on© 
essential factor for plant growth. However, it 
is obvious that sunlight is not necessary for a 
seed to sprout, or to germinate, as the seed is 
already sprouted before it reaches the rays of 
the sun. 
This complicated process continues from the 
time the young seedling reaches the upper crust 
of the earth until the plant finally matures. 
The leaves are regarded as the factory of the 
plant. They manufacture, by the aid of chlo¬ 
rophyll, the plant food from the various ele¬ 
ments that enter the leaves. But perhaps it 
has not yet been made perfectly clear as to 
how the plant is nourished from this food that 
is made in the leaves. The food must be re¬ 
moved from the leaves, or we would have large, 
bulky leaves, that would be the heaviest part 
of the plant. This removal of plant food takes 
place mostly at night, by a process known as 
translocation. The plant food is taken up in a 
stronger solution of water, and carried to the 
other parts of the plant, so that everything is 
in proper balance. 
From what has just been said, it can be seen 
that this process of manufacturing plant food 
could not take place to the maximum capacity 
of the plant, if the proper elements were not 
given to the leaves, and given in sufficient quan¬ 
tity. This problem brings us back to the fer¬ 
tility of the soil, once more. What if just one 
necessary element is lacking in the soil, so 
that the leaves cannot manufacture food enough 
to properly supply the plant with its needs? 
The result will be a plant retarded in growth, 
