No guidance through palpation or secretion. Leukæmia. Lymphadenoma.
Spleen a favorite culture ground for microbes. Congestions,
engorgements, ruptures. Safety valve to portal system and liver.
Rhythmic splenic contractions under reflex action.
The spleen even more than the pancreas is so deeply seated and so
surrounded by other organs, that its diseases are not readily
appreciable by physical examination, while the absence of any special
secretion excludes the possibility of diagnostic deductions through this
channel. Even the relation of the condition of the organ to the number
of the leucocytes and red globules fails to afford trustworthy
indications of disease, since leucocytes originate in other tissues as
well as the spleen, and the destruction of red globules may take place
elsewhere. Yet an excess of eosinophile leucocytes in the blood suggests
hypertrophy or disease of the spleen, and an excess of leucocytes in
general is somewhat less suggestive of disease of this organ (see
Leucocythemia). If adenoma is further shown, in enlargement of lymphatic
glands elsewhere there is the stronger reason to infer disease of the
spleen.
The physiological relation of the spleen to the blood especially
predisposes it to diseases in which the blood is involved. The
termination of splenic capillaries, in the pulp cavities, so that the
blood is poured into these spaces and delayed there, opens the way, not
only for the increase of the leucocytes, and the disintegration of red
globules, but for the multiplication of microörganisms which may be
present in the blood, and for a poisoning (local and general) with their
toxins. Hence we explain the congestions, sanguineous engorgements and
ruptures of the spleen in certain microbian diseases (anthrax, Southern
cattle fever, septicæmia, etc.)
We should further bear in mind that the spleen is in a sense a safety
valve for the blood of the portal vein, when supplied in excess during
digestion. In this way it protects the liver against sudden and
dangerous engorgements, but it is itself subjected to extreme
alternations of vascular plenitude and relative deficiency. This may be
held to take place largely under the influence of the varying force of
the blood pressure in the portal vein, but according to the observations
of Roy on dogs and cats, it is also powerfully influenced by muscular
and nervous action. He found rhythmic contractions of the organ due to
the muscles contained in the capsule and trabeculæ, repeating themselves
sixty times per hour, and which might be compared to tardy pulsations.
He further found that electric stimulation of the central end of a cut
sensory nerve, of the medulla oblongata, or of the peripheral ends of
both splanchnics and both vagi caused a rapid contraction of the spleen.
The spleen may thus be looked on not only as a temporary store-house for
the rich and abundant blood of the portal system of veins during active
digestion, but also as a pulsating organ acting under the control of
nerve centres in the medulla. That the various ascertained normal
functions of this viscus may be vicariously performed by others, as
shown in animals from which it has been completely extirpated, does not
contradict the occurrence of actual disease in the organ, nor the
baleful influence of certain of its diseases on the system at large.