ribs and diaphragm.

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535. _Scrofula, or consumption, frequently succeeds a depressed state
of the nervous system._ These diseases arise from the deposition of
tuberculous matter in different parts of the body. Those individuals
who have met with reverses of fortune, in which character and property
were lost, afford painful examples. Hundreds yearly die from the
effect of depressed spirits, caused by disappointed hopes, or
disappointed ambition.

_Illustration._ A striking instance of the effects of mental
depression is related by Laennec. In a female religious establishment
in France, great austerities were practised; the mind was absorbed in
contemplating the terrible truths of religion, and in mortifying the
flesh. The whole establishment, in the space of ten years, was
several times depopulated--with the exception of the persons
employed at the gate, in the kitchen, and garden--with that fatal
disease, consumption. This institution did not long continue, but
was suppressed by order of the French government.

536. _The purity of the blood is influenced by the condition of the
lungs._ When the bronchial tubes and air-cells have become partially
impervious to air, from pressure upon the lungs, from fluids in the
chest, from tumors, or from the consolidation of the cells and tubes
from disease,--as inflammation, or the deposition of yellow, cheesy
matter, called tubercles,--the blood will not be purified, even if the
air is pure, the lungs voluminous, and the respiratory movements
unrestricted, as the air cannot permeate the air-cells.

_Observations._ 1st. The twenty-three who escaped immediate death in
the Black Hole of Calcutta were soon attacked with inflammation of the
lungs, by which these organs were consolidated, and thus prevented
the permeation of air into their cells. This disease of the lungs was
caused by breathing vitiated air.

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535. Mention some of the effects of mental depression upon the body.
What is related by Laennec? 536. Does the condition of the lungs
influence the purity of the blood? Mention some of the conditions that
will impede the oxydation of blood in the lungs. What occurred to
those persons who escaped death in the Black Hole of Calcutta?

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2d. One of the precursory symptoms of consumption is the feeble murmur
of respiration in the upper part of the lungs. This condition of these
organs is produ