d granules, we go a step further in the problem
of vitality. When we say that certain nutritious principles are taken into
this circulating fluid by means of digestion and absorption, and that by
assimilation they are converted into the various tissues of the body, we
think we have solved the problem, and know just the essence of life
itself. But what makes the blood hold these nutritious principles in
solution until the very instant they come in contact with the tissue they
are designed to renovate, and then, as it were, precipitate them as new
tissue? You say they are in chemical solution, and the substance of
contact acts as a re-agent, and thus the deposit of new tissue is only in
accordance with the laws of chemistry. Perhaps this is so. Let us see as
to the proofs. In the analysis of the blood plasma, we find chlorides of
sodium, potassium and ammonium, carbonates of potassa, soda, lime and
magnesia, phosphates of lime, magnesia, potassa, and probably iron; also
basic phosphates and neutral phosphates of soda, and sulphates of potassa
and soda. Now in the analysis of those tissues composed principally of
inorganic substances or compounds, it will be seen that these same salts
are found in the tissues themselves.

So also the organic compounds lactate of soda, lactate of lime, pneumate
of soda, margarate of soda, stearate of soda, butyrate of soda, oleine,
margarine, stearine, lecethine, glucose, inosite, plasmine, serine,
peptones, etc., are found alike in the tissues and in the blood plasma.
That they are in solution in the plasma is well known,--that they are in
a solid or precipitated form in the tissues is also true,--and that the
tissues are supplied from the blood is also evident,--because the blood is
the only part that receives supplies of material direct from the food
taken and digested.

That carbonate of lime and phosphate of lime are precipitated or
assimilated from the plasma to form bone, is admitted by all
physiologists. That the carbonates and phosphates already deposited act
as the re-agent to precipitate fresh supplies from the plasma is not a
demonstrated fact, but may be inferred. So also with the other tissues.
Should this be admitted without positive evidence we would not then be at
the end of our problem;--for the question may be asked as to what causes
the first or initial deposit. Here we must stop and acknowledge our
ignorance.

But you may now ask what all this physiology and chemistry