Poverty of blood may result from various diseases, or from loss of blood, too long nursing, etc. Weakness accompanies it, of the kind above called exhaustion. An anaemic person is usually pale (though perhaps easily flushed by excitement), rather thin, and "nervous." There is a form of this disorder called progressive pernicious anaemia, which cannot be accounted for by ordinary causes, and which it is almost or quite impossible to cure by any treatment.

Plethora is the opposite of anaemia. In it, the red corpuscles of the blood are too numerous, and the blood itself is redundant in amount. A plethoric person is round and plump (not necessarily fat), with full blood-vessels and a high color. Such an one is more liable than others, in early life, to acute inflammations and active hemorrhages; after middle age to apoplexy.