52

ELEMENTS OF MATERIA MEDICA.

venient mode of effecting it is from a bladder; but for other ar.d morecomplete, though more costly methods, I must refer you to the works ofthe late Dr. Beddoes, and of the celebrated engineer, Mr. James Watt. —(■Considerations on the Medicinal Use, and on the Production of FactitiousAirs, 1796.)

f. Gastro-intestinal membrane. —We employ both extremities of thealimentary canal for the exhibition of medicines; the upper, however,more frequently than the lower. This mode of employing medicines iscalled the method by ingestion. Of all parts of the body the gastro-intes-tinal surface is the most useful for the application of medicines. Thisarises from the great susceptibility, the active absorbing power, and thenumerous relations, which the stomach has with almost every part of thebody. In many cases remote effects are more easily produced by thisthan by any other organ, as in the case of diffusible stimulants. Medi-cines which act by absorption are more energetic when applied to theserous membranes, the bronchial membrane, the cellular tissue, &c. Insome cases it is not only possible, but probable, that the stomach mayeither partially or wholly digest a medicine.

g. Recto-colic membrane. —Sometimes, though less frequently than thestomach, the rectum is employed for the application of medicines. It hasbeen asserted that the general susceptibility of the rectum is only one-fifthof that of the stomach, and that medicines take five times as long to ope-rate by the former as by the latter: hence it has been said that both thedose, and the interval between the doses, should be five times as great aswhen applied to the stomach. But this assertion is far from being uni-versally correct, though it may be so occasionally. Orfila asserts thatthose agents which operate by absorption, as opium and tobacco, aremore active by the rectum than by the stomach; and he assigns as areason the greater venous absorption of the rectum, and its less digestivepower. But this statement is in direct opposition to the experience ofalmost every practitioner. Whenever I have had occasion to employopium by way of enema, I always exhibit twice or three times the ordi-nary dose, without exciting any remarkable effects. Dr. Christison statesthat he has given two measured drachms of laudanum by injection, with-out producing more than usual somnolency, a quantity which, if Orfilalsstatement were correct, would probably prove fatal.

We apply medicines to the rectum sometimes with the view of alle-viating disease of this or of neighbouring organs (as of the uterus, blad-der, prostate gland, &c.j; at other times in order to irritate the rectum,and, on the principle of counter-irritation, to relieve distant parts (as thehead); sometimes to produce alvine evacuations, or to dissolve hardenedfieces; occasionally, also, when we are precluded from applying ourremedies to the stomach, on account of their unpleasant taste ana smell,the inability or indisposition of the patient to swallow, or the irritabilityof the stomach ; and, lastly, in order to destroy the small thread-worm(.Ascaris vermicularis :)

When the substances applied to the rectum are solid, we name themsuppositories (suppositoria, from suppono, to put under;) but when ofa fluid nature, they are termed clysters, lavements, or enemata.

Formerly suppositories were conical, or cylindrical, like a candle, and ofvariable size,—sometimes one or two inches long. They are now usuallymade globular, and of small size. They are employed to evacuate the