(From its resembling a nut). Aden. A gland; a distinct soft body, usually of a reddish colour, which separates a peculiar fluid from the general mass, either injurious to the system, or for some useful purpose in the animal economy. It has been doubted whether an artery without convolution may not be adapted for secretion. It is impossible to prove a negative; yet it appears highly improbable, unless the supposed secretion be merely a serous exhalation.

The glands are roundish bodies, seated in the cellular membrane, generally near the large vessels, from which they receive considerable branches: they are of different consistence, and various colours. Sylvius first divided them into conglobate, now called lymfihatic and conglomerate. (See Conolobata, and Conglomerata glan-dula). Malpighi added what he called the folliculus or simple gland; such as are found behind the ears, but more remarkably in the fauces.

Dr. Nicholls divides the glands into sinuous, tubular, and equal. A sinuous gland is one whose several follicles have their own excretory ducts, transmitting their fluid to a common basin, as the kidneys. The tubular is the same with the conglobate gland of Sylvius, of which the testes are an instance. In an equal gland the vessels are branched, as in the liver.

Glands are most commonly divided according to the nature of the fluids they furnish, into mucous, sebaceous, lachrymal, salivary, and biliary; but these distinctions are only the parade of science, and add little to its utility.

Ruysch proves, by subtle injections, that the substance of the glands is vascular, consisting of a ramifying artery, partly terminating in a vein, and partly in an excretory duct. But there is not the slightest evidence that the extremity of the artery forms a continuous canal with the excretory duct. On the contrary, a hollow cavity js probably interposed, in which the fluids stagnate, and in which the change principally takes place. Mr. Hewson, however, thinks that the little globular bodies called cryptae and follicule are only convoluted arteries.

In reality, however, the structure of glands is little known. From corroded injections we perceive only ramifications of vessels in angles peculiar to the organ, and constant in every individual; and on this regular arrangement a mechanical theory of secretion has been raised. In no instance, however, do we find that the injections pass by continuous vessels into the excretory ducts; and in very few will they, by any management, penetrate so far.

When the glands are swollen only, if hard, they are said to be indurated; if harder, and irregular in their feel, to be scirrhous; if, when hard, they are painful, they are styled incipient or occult cancers; if their hardness and pain continue, carcinomata, or inveterate occult cancers; and if the skin breaks, they are called ulcer-, ated and true cancers.

Indurated glands in children's necks are common, and of little importance. The lymphatic system in the

4X2 early periods is large, and from want of irritability often obstructed. These tumours, even though they apparently tend to suppuration, may generally be removed by the use of small doses of calomel, with sea water, in a sufficient quantity, daily to produce a gentle discharge from the bowels. Cicuta, sometimes recommended, is unnecessary, and often injurious. Should the glands not be painful, no application is necessary; but they should be kept perfectly cool. See Scrofula, Scirrhus, Cancer, Lupia, Naevus. Kirkland's Medical Surgery, vol. ii. p. 475.

On the nature and structure of glands see Sylvius, Malpighi, Ruysch, Cowper, Havers, De Bordeu, &x.

Glandula lachrymalis; lachrymal gland, is a hard conglomerate gland, situated in a cavity of the os frontis, within the orbit, above the external canthus. From the lachrymal gland, on the inside of the tunica adnata of the eye lid, six or seven excretory ducts perforate the tunica adnata by as many orifices, at the distance of a few lines from the tarsus, and evacuate a-saline aqueous fluid, called the tears, between the eye lid and the bulb of the eye. The extremities of very small arteries exhale also a moisture from the whole surface of the tunica conjunctiva, which, mixed with the liquor of the lachrymal gland, and the mucus of the Meibomian glands, moistens and lubricates the eye, and the inside of the eye lids.

Glandula lachrymalis, and innominata. See Caruncula lachrymalis.

Glandula pituitaria; a small greyish body, lying between the sphenoidal folds of the dura mater on the sella turcica. It is oval, white or greyish within, and sometimes apparently divided into two lobes. It is covered by the pia mater, and the opening of this covering is the extremity of the infundibulum. It has been supposed the seat of the soul, as it is the only single organ of the brain, but is probably a lymphatic gland.