274 
THE GARDENERS' CHRONICLE OF AMERICA 
Whatever may be the nature of the nitrogenous material 
which is applied to the soil, nitrates must be formed 
eventually before the nitrogen can be best utilized by 
plants. For example, dried blood, about one-eighth of 
which is nitrogen, must first undergo putrefactive fer- 
mentation or decay, brought about by the action of molds 
and micro-organisms, and the products thus obtained are 
acted upon by bacteria within the soil, which possess the 
power of changing them into nitrates, familiar examples 
of which are the nitrate of soda which is used as a man- 
ure salt and nitrate of potash or the medicinal saltpeter. 
The nature of such a salt as nitrate of soda may be better 
understood if we consider the substances from which it 
can be made. If the acrid, sour substance known as nit- 
ric acid be combined with caustice soda lye in certain 
proportions, a solution of nitrate of soda will be formed. 
Upon evaporation, the crystals of the salt will separate. 
This is a compound then composed of the nitric acid and 
the soda, and although less than one-sixth of it is nitro- 
gen, the remainder is just as truly a part of the salt, and 
is in no sense an adulteration. Phosphoric acid and pot- 
ash likewise constitute only parts of compounds or salts. 
A so-called complete commercial fertilizer is simply a 
mixtures of salts or substances which contain nitrogen, 
phosphoric acid and potash along with the ingredients 
which are parts of the compounds as truly as the soda is 
a part of the nitrate of soda, although they may not be 
essential as plant food. This explains in part, why the 
sum of the nitrogen, phosphoric acid and potash may 
perhaps constitute no more that one-fourth of the 
fertilizer. 
Although no single ingredient of a complete fertilizer 
can act independently of the others we have learned to 
associate certain tendencies of growth with the individual 
ingredients. If it is desired especially to promote the 
growth of leaves regardless of maturity and fruit produc- 
tion an abundance of nitrogen is used; whereas if the life 
cycle, including the production of fruit or seed, is to be 
completed early a liberal amount of phosphoric acid must 
be supplied. Potash does not seem to have so much in- 
fluence on maturity as the relative amounts of nitrogen 
and phosphoric acid, but it is of special importance in 
connection with plants which produce large quantities of 
carbohydrates, such as starch and sugar. 
Animal manure and most brands of commercial fertili- 
zers contain all three of the ingredients which have been 
considered above, but since for special purposes they may 
need supplementing it is important to be acquainted with 
the composition of the more common sources of plant 
food ingredients. 
Nitrogen may be supplied in nitrate of soda, sulphate of 
ammonia or dried blood, the rapidity of action decreasing 
in the order named. Phosphoric acid becomes most 
quickly available when added in acid phosphate. Bone 
and tankage contain not only phosphoric acid but nitro- 
gen and are fairly quickly available. In normal times 
potash is secured in the soluble sulphate and muriate. 
Wood ashes not only supply potash but also lime. Their 
main beneficial effect is frequently because they counter- 
act or neutralize an injurious degree of soil acidity. 
Most vegetables are sensitive to soil acidity, on which 
account it is important to give attention to the needs of 
the soil for ashes or lime. These substances also have 
important physical effects, and likewise promote the ac- 
tivity of the beneficial bacteria. 
No food can enter the plant except it be in solution. It 
becomes necessary, therefore, to learn whether anv 
changes take place in the fertilizing material after it i? 
applied, which would render it insoluble and thus in- 
capable of being taken up by the plant. Phosphoric acid 
in particular, even when applied in a soluble form, is in- 
clined to combine with oxides of iron and aluminum ex- 
isting within the soil and become insoluble before it can 
be utilized by the crop. 
The salts when once in solution within the plant are, as 
we have seen, carried through the tubular cells principal- 
ly , till they reach the green parts where a portion of them 
is used in connection with the formation of organized 
matter. 
One of the first products which makes its appearance 
in connection with the processes carried on in the green 
matter of the plant, with the help of the sun's light, is the 
well-known substance, starch; it assumes a beautiful 
color when treated with a solution of iodine and its gran- 
ules may then be easily seen with the aid of the micro- 
scope in thin sections of leaves. This same substance 
then, which constitutes so large a part of our food, is 
first formed in connection with the green coloring matter 
or chlorophyll of plants, i. e., principally in the leaves, 
and later in the life of the plant is found stored in special 
parts. The tuber of the potato is simply a thickened por- 
tion of the underground stem which serves principally as 
a receptacle for starch. How did the granules of inso- 
luble starch find their way from the leaves to the tuber? 
It would be impossible, obviously, because of their in- 
solubility, for them to pass from cell to cell through the 
cell-walls. It becomes necessary then to take into ac- 
count certain ferments which have been found within 
plants and which perform functions similar to those tak- 
ing place within our own bodies. Our saliva contains a 
ferment called diastase, which assists in converting our 
starchy food into sugar. The same ferment occurs with- 
in the plant ; it acts upon the starch granules observed 
within the leaves, bringing them into solution or con- 
verting them into sugar. 
.Movement away from the leaves can now begin 
through the cell sap, which, as was pointed out earlier, 
occupies the inner portion of many cells and serves 
among other purposes, to carry food for the nourishment 
of the protoplasm with which it is in contact. The layer 
of protoplasm which lies within the wall of every living 
cell, is capable of allowing the sap and its contents to 
pass through and come in contact with the cell-wall 
through which it permeates to the adjoining cell. The 
flow of sap from the leaves, containing the substances 
which are produced there, is not entirely from one short 
cell to another, but takes place al>o through long tubes 
similar to those which partly conveyed the water and dis- 
solved salts from the soil to the leaves. These long 
tubular cells placed end to end form canals which pass 
entirely through the plant. The canals which serve to 
carry crude material to the leaves lie alongside of those 
which conduct the more finished products in the opposite 
direction and consisting as they do of numerous forms 
differently marked and pitted on the inside, make up a 
bundle which indeed has received the name of vascular 
bundle. Numerous bundles of this kind are distributed 
throughout the plant with branches striking out in all di- 
rections. The tiny veins which may lie seen bv the un- 
aided eye in leaves, represent some of these branches. 
These bundles and their branches serve then, as a means 
for the more rapid transference of material from one 
part of the plant to another. This material, it should be 
remembered, must be in a liquid or semi-liquid condition 
when it is in transit and in view of the fact that it is 
frequently in a solid state at the beginning of its travels 
ami that it is usually deposited as a solid finally, it is 
apparent that many physical and chemical changes must 
take place. These changes appear all the more compli- 
cated when the materials themselves are insoluble in the 
cell sap. and instead of simply dissolving as sugar would. 
