AROMA AND AROMATICS. Aroma is the supposed principle of odour in plants,' formerly called by Boerhaave Spiritus Rector. This quality generally resides in the essential oil ; but there are some vegetables that have a strong odour which yield but little or no essential oil, as the jessamine and the violet ; or when an oil in small quantity is procured from them, it has not a powerful smell.
Aromatics exercise a peculiar influence over the digestive powers, and are possessed of more or less odour or fragrance. Of this odour, by which they can at all times be recog nised, the most usual vehicle is an essential or volatile oil, as just stated. Indeed, volatile oil exists in all aromatic plants, and in every part except the cotyledons, save in the nutmeg and a very few other seeds; but this aromatic oil does not reside in the same part in every kind of plant.
Aromatics are seldom applied to the organ of smell for the purpose of influencing the system in a remedial manner, but are usually introduced into the stomach. As all aromatics contain volatile oil, their action is generally referred to this principle ; but there cannot be a doubt that the more fixed principles which they contain contribute greatly to their effect. Volatile oils, when separated, act
chiefly on the nervous system ; but aromatics influence the digestive organs, the function of assimilation, and the circulation. The neces sity for the employment of aromatics is greater in warm climates and weather than in cold ; and we find the plants which furnish them grow in the greatest abundance in hot countries. Throughout the East Indies the natives restore the powers of the stomach by chewing betel, which consists of slices of the areca nut, sprinkled with fresh lime, wrapped tip along with some aromatic in a leaf of the piper betel. The Indians of South America use the Erythr6xylum Peruvianum ( called coca) along with the leaves of the Chenoptidium Quinoa, mixed with quicklime, to stimulate the impaired powers of the stomach during their long and toilsome journeys over the heights of the Andes. On the same principle, the Europeans who visit tropical countries use curry and other hot dishes. But in every quarter of the globe we find condiments used along with all articles difficult of digestion, especially vegetables, fish, and young meat, such as veal.