Gland

Collier's New Encyclopedia (1921)

a term at first vaguely applied to any smooth, round viscus, but which is now limited to such of these as secrete-i. e., separate by a process of cell growth, certain constituents of the blood which are afterward poured out from the gland by means of a duct. They are divided into lymphatic and secreting glands. Lymphatic glands are bodies resembling glands in form, but not possessing ducts for secretion, so that their products must be conveyed to them by lymsanguiferous vessels. Exphatic or amples, the spleen, the thyroid body, the thymus gland, the suprarenal capsules, the pituitary body, the follicular glands at the root of the tongue and the lymphatic glands. Secreting glands are the typical kind of glands to which the name is now very frequently restricted. They collect and discharge at particular parts various matters derived from the organism, that these may be further employed for special purposes in the economy, or simply eliminated as redundant material or waste products. In the latter case the term used is excretion. In this process the nucleated cell takes a prominent simple recess part. When there is a formed of secreting membrane, the gland is said to be simple. Examples of this structure occur in the mucous membrane of the stomach, the intestines, etc. When the cavity is subdivided as well as extended with the view of increasing the secreting surface, the gland is said to be again subagain The latter are compound. divided into first tubular and second sacular or racemose glands. The glands of the testicle and those of the kidney are tubular; the salivary, lachrymal, and mammary glands, and most of the glands opening into the mouth, the fauces, and the windpipe are racemose glands. In botany cells or aggregations of cells distinguished from their neighborhood by containing resinous, fragrant substances. oily, sugary, or The walls of the cells generally become degenerated, and are ultimately dissolved, a cavity being thus formed as seen in the rind of the orange and lemon. In other cases the secretion is discharged externally. Ordinary glands occur in almost all the tissues of plants.