During the digestive processes the starchy, saccharine, and albuminoid
elements of food are dissolved, and the fatty matters are emulsified.
A uniform milky solution is thus formed, which is rapidly absorbed
into the general circulation; some of it passes directly through the
walls of the vessels into the blood, and some is taken up by the
lacteals and reaches the vital fluid by traversing the complicated
series of tubes known as the absorbent system, and the numerous glands
connected with it. The chief function of the starchy and fatty food
elements is to keep up the physical temperature, by being submitted to
oxidation in the organism; therefore it is not necessary that they
should experience any vitalizing change, but are fitted to discharge
their duties in the vital domain by simply undergoing the solution
that fits them for absorption. But the materials intended to enter
into the composition of the body must be developed into living blood,
in order to be fitted to become part and parcel of the organs by which
power is evolved, and through the use of which we see, hear, feel,
think, and move. This wonderful process begins and is carried forward
in the absorbent system, which has been described by Dr. Carpenter as
a great blood-making gland. But the vital transformation is not
completed until the nutritive materials have been submitted to the
action of the liver, and afterward to the influence of oxygen in the
capillaries of the lungs. The food that was eaten a few hours before
is thus converted into rich scarlet arterial blood, if every part of
the complex vitalizing processes has been properly conducted. But the
influence of oxygen is requisite, not only to complete the
vitalization of the embryo blood in the lungs, it is an absolutely
essential element in every step of the vitalizing process in the
absorbents.
The average quantity of food required to sustain an ordinary man in
health and strength, I have previously stated, is about two pounds
avoirdupois daily, and an equal weight of oxygen is necessary to the
integrity of the vitalizing processes undergone by the food, and to
maintain the physical temperature. When the requisite supply of oxygen
is reduced, the extrication of heat within the system is promptly
diminished, but the vitalization of digested food is unfavorably
affected much more slowly, but with equal certainty. If the quota of
oxygen existing in the arterial blood of the vessels whose duty it is
to supply the vital fluid to the absorbent system, be inadequate to
enable these operations to go on properly, the life-giving processes
must necessarily be imperfectly accomplished. Under these
circumstances the digested material is imperfectly vitalized, and is
therefore inadequately fitted to be used in building up and repairing
the living body. But its course in the system cannot be delayed, much
less stopped.
The blood possesses a definite constitution, which cannot be
materially altered without the rapid development of grave, perhaps
fatal consequences. The nutritive matters received into the blood must
be given up by it to the tissues for their repair, whether such
materials are well or ill fitted for the vital purposes. Dr. B.W.
Carpenter, of London, the celebrated physiologist, makes the following
pertinent statements on this subject, which I condense from his great
work on physiology: "We frequently find an imperfectly organizable
product, known by the designation of tubercular matter, taking the
place of the normal elements of tissue, both in the ordinary process
of nutrition, and still more when inflammation is set up.
From the examination of the blood of tuberculous subjects it appears
that, although the bulk of the coagulum obtained by stirring or
beating is usually greater than that of healthy blood, yet this
coagulum is not composed or well elaborated fibriae, for it is soft
and loose, and contains an unusually large number of colorless blood
corpuscles, while the red corpuscles form an abnormally small
proportion of it. We can understand, therefore, that such a constant
deficiency in capacity for organization must unfavorably affect the
ordinary nutritive processes; and that there will be a liability to
the deposit of imperfectly vitalized matter, instead of the normal
elements of tissue, even without any inflammation. Such appears to be
the history of the formation of tubercles in the lungs and other
organs.
When it occurs as a kind of metamorphosis of the ordinary nutritive
processes and in this manner, it may proceed insidiously for a long
period, so that a large part of the tissue of the lungs shall be
replaced by tubercular deposit without any other sign than an
increasing difficulty of respiration." These views are strongly
corroborated by the following facts:
In making post mortem examinations of persons who have died of
consumption, tubercles of different kinds are found in the same
subject; some of these, having been deposited during what is called
the first stage of the disease before the breathing powers were much
impaired, bear evident traces of organization in the form of cells and
fibers more or less obvious, these being sometimes almost as perfectly
formed as living matter, at least on the superficial part of the
deposit, which is in immediate contact with the living structures
around.
This variety of tubercle has a tendency to contract and remain in the
lungs without doing much injury. But as the disease progressed, and
the breathing capacity progressively diminished, tubercular matter
occurs, evincing less and less organization, showing a tendency to
break down and cause inflammation in the surrounding lung tissue,
until at last we find crude yellow tubercles that have become
softened, and formed cavities almost as soon as they were deposited.
Some cases of chronic consumption pass in a few months through the
various stages from the deposit of the first tubercle to a fatal
termination.
The progress of the disease is determined largely by the nature of the
tubercular matter at the time it is deposited.
The variety of matter which has been partially vitalized commonly
exists in small quantity, has a strong tendency to maintain its
semi-organized condition unchanged by time, and rarely causes
inflammation.
A small or moderate quantity of this sort of tubercle exists in the
lungs of many persons, in whom it produces no tangible symptoms, and
who are therefore quite unconscious of its presence; and even when it
does exist in sufficient quantity to develop the symptoms of lung
disorder, the progress of the disease is slow, often continuing for
many years. It constitutes a variety of consumption which is specially
amenable to proper treatment. On the other hand, the soft, yellow,
cheesy, tubercular matter, which is totally destitute of any vitality,
is too often deposited in large quantities, acts on the adjacent lung
tissue as an active irritant, causes inflammation, undergoes
softening, forms cavities, defies treatment, and rapidly hurries the
sufferers to a premature grave. These facts, taken in connection with
the immunity from lung diseases enjoyed by those whose respiratory
capacity is well developed and properly used, as well as the
beneficial effects that are promptly secured in the favorable
varieties of consumption by any important increase in the vital
volume, I believe fully justify the statement that _tubercles are the
results of defective nutrition directly traceable to inadequate
respiratory capacity_, either congenital or acquired--in other words,
tubercles are composed of particles of food which have failed to
acquire sufficient life while undergoing the vital processes, because
the person in whom they occur habitually breathed too little fresh
air.
Persons who possess what is called the scrofulous constitution are
specially liable to the occurrence of tubercular matter when their
respiration is defective, or they are exposed to any other influences
that favor its development in the organism. But habitually defective
respiration, or the breathing of an atmosphere containing too little
oxygen, which practically amounts to the same thing, has a very
powerful tendency in the same direction, in persons who are apparently
as free from scrofulous taint as any human being can be.