1 Preyer, Die Blutcrystalle. Jena, 1871.

but the heart is not affected. In mammals they cause congestion of the stomach and intestine, and diarrhoea. They produce paralysis both of sensation and motion. The blood-pressure falls. This is due to paralysis of the vaso-motor nerves, especially of the intestine, resembling that produced by arsenic, antimony, emetin, and colchicin.

Iron is eliminated to a considerable extent by the bile (p. 405), by the mucous membrane of the intestine, and by the kidneys.

Uses of Iron. - The ferrous salts are rarely employed for their local action. The ferric salts are used as styptics. The strong solution of perchloride may be employed to arrest bleeding from the cavity of a tooth after extraction, or to stop the oozing from a wound where it is impossible to ligature all the bleeding points. When diluted it may be used as an injection to arrest haemorrhage from the nose, or may be injected into the cavity of the uterus to arrest bleeding from that organ. Mixed with laudanum it has been used as an injection in gonorrhoea and gleet. Both ferrous and ferric salts are administered internally in order to produce the general action of iron in increasing the' blood-corpuscles. They differ to some extent, however, the ferrous salts having a less astringent action on the intestines than the ferric. In cases where the mucous membrane of the alimentary canal is irritable this is advantageous, as in such instances the ferric salts might cause digestive disturbances and headache. In other instances, however, especially those where the tongue is pale and flabby, the more astringent preparations are to be preferred. The chief use of iron is as a haematinic, and the condition in which it is most beneficial is where we have anaemia and chlorosis, whether these be due to loss of blood, imperfect nutrition, chronic discharges, scrofula, syphilis, malarial poisoning, amenorrhoea or albuminuria, or be consequent upon acute febrile disease; but it is also serviceable in a number of disturbances of the nutritive and nervous systems. It has been recommended in large doses in cases of blood-poisoning, such as diphtheria and erysipelas, and in nervous diseases like chorea, epilepsy, giddiness, formication, twitching of the fingers, and subjective sensations of light and heat or cold to which some patients are liable, especially about the climacteric period. It is also used internally in order to diminish discharges from the mucous membranes of the intestines, as in chronic diarrhoea and dysentery, and from the vagina in leucor-rhoea. It acts as an astringent on the kidney, lessening the amount of blood in haematuria, and sometimes the amount of albumen in albuminuria. It is also a useful adjunct to diuretics in cardiac and renal dropsy (p. 338).