THE SCIENCE OF NUTRITION 113the body loses its former powers. Once elastic, healthy,
alert, pliable, active, and sensitive, it becomes rigid,
slow, and insensible. Finally, it dies of old age.
The question now arises, What is the cause of this
gradual ossification of the body, bringing rigidity,
decrepitude and death? From the purely physical
standpoint, chemists seem to be unanimous in the
opinion that it is principally an increase of phosphate
of lime (bone matter), carbonate of lime (common
chalk), and sulphate of lime (plaster of Paris), with
occasionally a little magnesia and an insignificant
amount of other earthy matters.
The only difference between the body of old age
and that of childhood is the greater density, toughness
and rigidity, caused by the greater proportion of
calcareous, earthy matter entering into the composition
of the former. The bones of a child are composed of
three parts of gelatine to one part of earthy matter. In
old age this proportion is reversed. What is the source
of this death-dealing accumulation of solid matter?
It seems to be axiomatic that the entire body is
nourished by the blood and that everything contained
in the body, of whatever nature, has first been in the
blood. Analysis shows that the blood holds earthy
substances of the same kind as the solidifying agents—
and mark!—thearterial blood contains more earthy
matter than thevenous blood.
This is highly important. It shows that in every
cycle the blood deposits earthy substances. It is
therefore the common carrier that chokes up the
system. But its supply of earthy matter must be