=General Considerations:=—It has been said that each individual is
a part of all the generations which have preceded him. In the same
way it might be said that every drop of our blood is a part of every
other cell in our bodies. The other tissues are able to maintain their
existence only through the ministrations of the blood and in turn
the blood derives its own substance from tissues which it supplies.
We are accustomed to speak of certain organs as being those of blood
formation, yet it is true that every tissue furnishes its quota of
blood composition, making up the mass which we call blood.
It is in one way an algebraic sum of good and baneful substances,
without which there can be no normal function, and sometimes being of
itself a menace as well as an aid to other tissues, as in sepsis. There
can be no perverted function of any tissue without there being a direct
effect upon the blood. We may not always be able to measure this effect
with our present laboratory methods. We may not be able to detect
clinically the result of this alteration of the blood stream because of
compensatory influences, dilution, phagocytic action, enzymatic action,
oxidation, and the intricate processes of excretion. It must also be
remembered that normal blood is not of a certain definite chemical or
physical composition. It must vary from minute to minute according to
the normal metabolic phenomena which make up our succession of events
associated with life.
But comparatively little is known about this most important fluid. We
have accumulated data regarding morphology and relative numbers of
its formed elements and their behavior when sufficient abnormality is
present to upset their wonted balance of arrangement. We have an ever
widening field of investigation in the blood plasma in which we are
constantly being told of newly discovered complexities. Certainly the
field of the unknown is big enough to contain our unexplained blood
reactions.
It is probable that as our knowledge increases our number of diseases
really considered as true blood diseases will decrease and be shown to
be the effect of blood passing through certain pathologic tissues of
the body. We can measure the number and proportion of formed elements,
and the relative efficiency of the erythrocytes by the amount of
hemoglobin which they carry. The genesis of the formed elements is to
be kept in mind in considering therapy. The erythrocytes and granular
cells developing in adult life, principally from the red marrow, leads
our attention in decrease or increase of these particular cells to the
greatest aggregation of red bone marrow which happens to be in the
ribs. The anatomical relation of the ribs to the spine would seem to
render them very liable to disturbances of nutrition and nerve control
as a result of structural maladjustment and clinically this presumption
is verified. Limitation of the motion of the thoracic spine is perforce
accompanied by costal inactivity with disuse effects upon the red
marrow and eventually upon the relative content of the blood stream.
We can measure the efficiency of the erythrocytes in carrying oxygen
to the tissues by measuring the relative amount of hemoglobin which
a given volume of blood contains. The actual changes taking place in
blood character are often thus sufficiently indicated for us in terms
of our present methods of examination, to at least aid in the arrival
at a diagnosis. We sometimes have to remember that the adaptation to
abnormality may be efficient enough to keep the apparent significance
from telling the “whole truth.”