PHYSIOLOGICAL CLASSES OF MEDICINES.

95

pass into the blood, and act on the kidneys in their passage throughthese organs.

9. Emmenagogues (emmenagoga, from qu/n/va, the menstrual dis-charge, and ay I,), to lead or convey), are agents supposed to have theproperty of exciting the catamenia. As the suppression or retentionof this discharge may be occasioned by very different circumstances,no one agent can be expected to prove emmenagogue in all or evenin many cases. Deficient menstruation is rarely, perhaps, an idiopathicdisease, but usually a morbid symptom merely; and, therefore, thoseagents which remove it must be relative,—that is, must have reference tothe disease which produces it. Thus when deficient menstruation isconnected with a deficiency of power in the system, tonics and stimu-lants are the best remedies. Again, in plethoric habits blood-lettingand other debilitating agents are those most likely to be serviceable.

But the term emmenagogue is usually employed in a more limitedsense, to indicate those substances which are supposed to possess aspecific power of affecting the uterus and of promoting the catamenialdischarge. There are, however, few bodies to which this definition canbe strictly applied. Indeed, two reasons have led some pharmacologicalwriters to doubt the existence of any medicines which can be properlytermed specific emmenagoges, namely, the uncertainty of all the meansso named, and the uterus not being an organ intended for the excretionof foreign matters.

The substances usually regarded as specific emmenagogues are, forthe most part, medicines which, when taken in large doses, act as drasticpurgatives, or which stimulate the urinary organs in a very marked man-ner. Such are savin, black hellebore, aioes, gamboge, cantharides, &c.They excite the pelvic circulation, give rise to a sensation of bearingdown of the womb, especially in females disposed to procidentia uteri,increase uterine ha3inorrhage, or the menstrual discharge, when givenduring these conditions,-—and when administered in chlorosis or amenor-rhcea, sometimes bring on the catamenia.

The only agent possessing an unequivocal specific influence overthe uterus is the ergot of rye. But this agent seems rather to promoteuterine contractions than the menstrual function,—though it has onmany occasions been successfully employed in amenorrheea.

Class 7. Abortiva seu Acceleratores Partus. —These are agentswhich increase the parturient efforts of the womb. At present, however,only one substance is known which possesses this property, and that isthe ergot of rye, which will be spoken of hereafter.

Class 8. Caustics ( caustica, from Kata, I burn). —These bodiesdisorganise by a chemical action. They are sometimes termed poten-tial cauteries (cauteria potentialia), to distinguish them from fire orthe actual cautery. The stronger caustics, as potassa fusa, have beentermed escharotics or erodents; while the milder ones, as sulphate ofcopper, have been denominated catheretics or cauterants.

The following substances are those usually employed as caustics: —the strong acids (sulphuric, nitric, hydrochloric, phosphoric, and acetic),the alkaline substances (potash, soda, ammonia, and lime), and variousmetallic preparations (as the nitrate of silver, chloride of antimony, sul-phate and acetate of copper, chloruret of zinc, binoxide and bichloruretof mercury, and arsenious acid.) Some of these become absorbed, and