Description and Properties.-A white, crystalline powder, of an acid reaction, a faint, amygdaloid odor, and an intensely sweet taste. One part of saccharin in 70,000 parts of water will impart to the solution a decidedly saccharine flavor, the drug being nearly 300 times sweeter than cane-sugar. Saccharin is slightly soluble in water, 1:400; soluble in 30 parts of alcohol; and freely soluble in glycerin. The commercial article is usually very impure. Dose.--2 grains (0.03-0.12 Gm.). Physiological Action.-In a neutral or alkaline medium saccharin acts as an antiseptic. Internally it exerts no notable influence. It is said that when mixed with food it interferes with the action of saliva upon starch, and it is thought to retard the action of the other digestive ferments. The drug is not decomposed in the body, and is eliminated by the kidneys unchanged, increasing the amount of chlorides excreted in the urine, which fluid is so influenced by the drug that it does not so readily undergo fermentation. Therapeutics.-Externally and Locally.—Saccharin is used as a mouth-wash, being especially beneficial in aphtha. Felici of Rome highly recommends the application of a solution of saccharin. in ozena. Internally. The principal use of the drug is as a substitute for sugar in cases of diabetes. Dr. James Little recommends saccharin in chronic cystitis with ammoniacal urine. The drug is extensively used in various elixirs, syrups, etc. to overcome the bitterness of quinine and other bitter alkaloids. Administration.-Saccharin should be given in solution. GROUP XIV.-CATHARTICS. CATHARTICS or PURGATIVES are substances which cause hurried evacuation of the bowels either by direct local irritation of the intestinal mucous membrane or by setting up an osmotic current from the tissues toward the lumen of the intestines, causing an accumulation of fluid in the bowels-in both cases causing increased peristalsis and watery or semisolid evacuations. Mechanism of Purgation.—It should be remembered that the epithelial surfaces through which the substances needful to the body enter it, and the waste-products leave it, are physiologically outside the body. The mucous membrane of the alimentary canal is in a sense as much external as the skin covering the surface of the body and is subject to the same irritating influences. The muscular mechanism of the intestines is somewhat peculiar in that it possesses the power to rhythmically contract and relax in a wave-like manner (peristalsis), the peristaltic waves travelling downward. These rhythmical movements of the intestines carry their contents along their lumen from the cardia to the rectum, and are to a large extent independent of the central nervous system, although in a way controlled by a nervous mechanism. The normal contents of the small intestine are fluid, and are passed into the large intestine as such. In their passage along the large bowel the fluid part is largely absorbed and the semisolid part remaining is passed on into the rectum as feces. In order that any substance may act as a purgative it must change the normal contents of the bowels in such a way as to cause fluid or semisolid evacuations. When a substance locally irritates the intestinal mucous membrane the intestines respond by increased peristalsis, which hurries the fluid contents of the small intestine through the large bowel so rapidly that absorption does not take place and the feces are evacuated in a fluid form. While increased peristalsis may be caused by action on the nervous mechanism of the intestines the exact modus operandi is imperfectly understood, and until the action of drugs on such mechanism is more thoroughly investigated we must assume that the action of purgatives is due chiefly to their local influence. Cathartics may be classified according to their various actions, the following table serving to show how and where the various drugs exert their several influences: 2. Classification according to their Manner of reaching the Intestinal 3. Conditions of the Intestines affecting the Action of Drugs. (Drugs marked with an asterisk (*) are here given in detail; others are described elsewhere.) 4. Classification according to the Anatomical Portion of the Intestinal (Drugs marked with an asterisk (*) are here given in detail; others are described elsewhere.) of Intestinal peristalsis is increased probably by the stimulation I. The intestinal muscles (moderate stimulation); 2. The afferent nerves connecting the intestinal mucous membrane with Auerbach's ganglia; 3. Auerbach's ganglia; 4. The ends of the efferent nerves passing from Auerbach's ganglia to the intestinal muscles; 5. The ends of the afferent nerves passing from the intestinal mucous membrane to the brain; 6. The motor centers in the brain; 7. The ends of the motor nerves terminating in Auerbach's ganglia. Depression of 8. The inhibitory motor center; 9. The ends of the inhibitory motor nerves terminating in Auerbach's ganglia; 10. The inhibitory motor center in the suprarenal plexus. It will be seen that any substance which stimulates the motor apparatus or depresses the inhibitory motor mechanism will increase peristalsis. Intestinal secretion may doubtless be promoted by any substance which serves to stimulate the secretory or the vaso-dilator apparatus, or to depress the inhibitory secretory or vaso-constrictor mechanism. The methods by which absorption is diminished are not thoroughly understood, but it is known that 1. By increasing peristalsis and hastening the removal of fluid 3. Substances which in some manner affect the columnar process. It is apparent that certain drugs produce various effects, and that their mode of action varies according to the size of the dose and occasionally with the idiosyncrasy of the patient. Nearly all cathartic drugs act by some local influence upon the |