On the Intestines. - Small doses increase the movements of the intestines. This action is probably due to paralysis of the inhibitory fibres of the splanchnic, since stimulation of the peripheral end of the cut splanchnic will cause arrest of movement in the unpoisoned, but not in the poisoned, animal. Moderate doses completely arrest peristaltic movements, but the muscular fibres of the intestine retain their irritability. Local irritation causes a local contraction but no peristalsis. This is probably due to paralysis of the intestinal ganglia.

Large doses stop the movements and paralyse the involuntary muscular fibres of the intestine, so that they only contract feebly, or not at all, when directly irritated.

The Temperature is increased by small doses, lessened by large ones.

Certain animals, especially pigeons and rodents, such as rabbits, guinea-pigs, and rats, are peculiarly insusceptible to the action of atropine. It is not improbable that the insusceptibility of rodents to the action of atropine depends on the very slight tonic action which the vagus exerts on the heart in them in their normal condition. When it is paralysed there is little change in the circulation, while in dogs the case is very different (p. 287).

Methyl- and ethyl-atropine paralyse the ends of the motor nerves, but do not tetanise; they, however, retain the action of atropine on the eye, heart, etc.

Uses. - Locally applied, belladonna lessens irritability and pain, and is hence used as a lotion in photophobia.

Solution of atropine is employed to dilate the pupil and paralyse accommodation in many conditions which have already been mentioned (p. 225). Migrainous attacks frequently depend upon astigmatism, hypermetropia, or other visual disturbances, and an attack may sometimes be cut short by the local application of atropine to the eye.

In the form of a plaster or liniment over the tender spots, it is useful in myalgia, neuralgia - especially supraorbital and intercostal neuralgia - pleurodynia, hypersensitiveness of skin, and irritability of the chest muscles seen in phthisical patients. The pain arising from old adhesions due to pleurisy is relieved by a belladonna plaster.

In the form of ointment it lessens pain and spasm in fissure of the anus and the pain and itching of haemorrhoids.

It is useful in checking local sweating on the head, hands, or feet, in the form of the liniment two or three times a day.

Atropine is used internally to check the sweating of phthisis and other exhausting diseases, in doses of 1/200 gr., gradually increased. It may be given in pill, or mixture, or hypodermically. The beneficial effect may here be due to paralysis of nerves of sweat-glands, but is probably due also to the stimulating effect on the respiratory centre (p. 443).

Belladonna stops the secretion of milk, and is hence used locally, in plaster or with glycerine (1 in 4), when the mother from any cause is unable to suckle her child, and the breast becomes swollen and inflamed.

In leucorrhoea with ulceration of the os uteri, a pessary made up of 2 gr. of ext. belladonnae, with 7 gr. of tannin, and cacao butter q.s., is very useful (Trousseau).

Given internally atropine is useful in extreme salivation, as in mercurial ptyalism. In chronic constipation, relief is often afforded by small doses of 1/4-gr. of the extract of belladonna; in children the tincture in a proportionate dose is more suitable than the extract. Its action here may be due to diversion of a stimulus from the inhibitory to the motor fibres of the splanchnic, or to paralysis of the inhibitory fibres of the splanchnics (p. 386). It lessens griping, hence it is a useful adjunct to purgatives. It is useful in cases of spasm of involuntary muscles, as in lead colic, simple colic, asthma, and in the spasm set up by renal and biliary calculi (cf. p. 171).

Internally it is useful in palpitation due to cardiac strain (p. 299), and sometimes gives relief in angina pectoris. One of the most useful applications in all cases of palpitation, whether accompanied by pain or not, is a belladonna plaster to the cardiac region. As atropine, while it appears to lessen the excitability of the ends of the vagus in the lung, excites the respiratory centre, its action in preventing cough is slight and uncertain. As it has the power of completely arresting secretion from the bronchial tubes it is useful in cases where there is excessive secretion, but where the bronchial mucous membrane is already too dry, it is injurious (p. 250). In incontinence of urine in children belladonna is a most useful remedy. It probably acts by lessening the irritability of the bladder. It is also very serviceable in irritability of the bladder with frequent micturition in adults (p. 445).

In epilepsy and chorea it is not of much use, but in frontal headaches it is useful in doses of 3 min. of tincture every three hours.

Atropine has been given internally for urticaria; it sometimes produces striking, though temporary, effects in hyperi-drosis.

As an antidote to opium, 4 min. of liquor atropine, B.P., may be injected subcutaneously, and repeated every quarter of an hour until the pupil dilates.

It has also been used in poisoning by Calabar-bean, and has been found useful in chloroform-poisoning, when death is impending from stoppage of the heart. Doses sufficiently large to paralyse the inhibitory apparatus must be used.