The chapter on hyperaemia naturally leads to a passing consideration of the opposite state, namely ancemia. Just as we have before treated only of local hyperaemia, we shall here, in like manner, limit ourselves to the subject of local anaemia. It comprehends both oligaemia, or an insufficient measure of blood in relation to what experience has shown to be its just standard, and true anaemia of an organ.

It is present under various conditions:

1. As the partial manifestation of general anaemia.

2. As the consequence of hyperaemia of one or more other organs.

3. As the result of coarctation and closure, or orificial obstruction of the vascular trunk supplying the diseased organ or part, pending the establishment of a compensating collateral circulation.

4. As the effect of external or internal pressure upon an organ, and its consequent inadequate injection; anaemia of the lungs from pleuritic effusion; anaemia of textures the interstices of which are filled up with morbid products, as in hepatization of the lungs, in fatty infiltration of the liver.

5. As a consequence of decay of the vascular apparatus of an organ affected with atrophy, whether primary or secondary, more especially atrophy with condensation (concentrical wasting).

The effects of anaemia are pallor, collapse, and shrivelling of the textures, weakening and eventual extinction of their function.

Anaemia is momentous proportionately to the vital importance of the diseased organ, and to its exigencies with respect to the supply of blood. Thus, anaemia of the brain, of the lungs, of muscle, is of the highest import.