"If an excited substance be brought near a ball made of pith, or cork, suspended by a silk thread, the ball will, in the first place, approach the electric, as at a, indicating an attraction towards it, and if the position of the electric will allow, the ball will come into contact with the electric, and adhere to it for a short time, and whill then recede from it, showing that it is repelled, as at b." -Comstock 1850

Electrical Attraction

"If an excited substance be brought near a ball made of pith, or cork, suspended by a silk thread, the…

This illustration shows the cross-section of a stem of Botrychium: p, pith; x, xylem; m, ray; c, cambium; ph, phloem; e, endodermis; cr, cortex.

Botrychium

This illustration shows the cross-section of a stem of Botrychium: p, pith; x, xylem; m, ray; c, cambium;…

"Transverse section of an open fibro-vascular bundle. c, cambium; cb, continuation of cambium between the fibro-vascular bundles; g, large pitted vessels; t, smaller pitted vessels and spiral vessels intermixed with wood-cells; y, inner phloem layers; bm bast fibers; m is the parenchyma of the pith; r, is the cortical parenchyma. Immediately external to the bark lies the bundle sheath of cells filled with starch." — Encyclopedia Britanica, 1893

Cambium

"Transverse section of an open fibro-vascular bundle. c, cambium; cb, continuation of cambium between…

"One of the simplest instruments of this kind consists of a metallic needle, terminated at each end by a light pith-ball, which is covered with gold leaf, and supported horizontally at its centre by a fine point.." -Comstock 1850

Electroscope

"One of the simplest instruments of this kind consists of a metallic needle, terminated at each end…

"Exogen. 1. Section of a branch of three years' growth: a, medulla or pith; b b, medullary sheath; e e, medullary rays; c c c, circles of annual growth; d, bark. 2. Netted veined leaf (oak). 3. Dicotyledonous seed: a, cotyledon. 4. Germination of dicotyledonous seed: a a, seed-leaves or cotyledons; o, plumula. 5. Exogenous flower (crowfoot)." -Whitney, 1911

Section of Branch Showing Exogen

"Exogen. 1. Section of a branch of three years' growth: a, medulla or pith; b b, medullary sheath; e…

"<em>A</em>, membrane of hair follicle, showing cells with nuclei and pigmentary granules; <em>B</em>, external lining of root sheath; <em>C</em>, internal lining of root sheath; <em>D</em>, cortical or fibrous portion of hairshaft; <em>E</em>, medullary portion (pith) of shaft; <em>F</em>, hair bulb, showing its development from cells." &mdash; Blaisedell, 1904

Hair follicle

"A, membrane of hair follicle, showing cells with nuclei and pigmentary granules; B,…

"Longitudinal tangential section of [maple], showing the ends of the medullary rays." - Century, 1889

Longitudinal Tangential Section of Maple

"Longitudinal tangential section of [maple], showing the ends of the medullary rays." - Century, 1889

"Longitudinal radial section through the wood of a branch of maple one year old: P, pith; B, bark." -Century, 1889 In botany, Medullary rays refer to a characteristic found in woods. In this context the term refers to radial sheets or ribbons extending vertically through the tree across and perpendicular to the growth rings. Also called pith rays or wood rays, these formations of primarily parenchyma cells allow the radial transmission of sap.

Medullary Rays of Maple

"Longitudinal radial section through the wood of a branch of maple one year old: P, pith; B, bark."…

"Diagram showing some types of unusual growth in thickness...C, portion of a cross section of stem of Gnetum scandens; 1, 2, and 3 are successive rings of growth; m, is the pith; b, is a sclerenchyma ring. The xylem portions with the exception of the larger tracheal tubes are shaded, while the medullary rays, phloem and tissues intervening between the rings of growth and the outer cortes tissues are left white." -Stevens, 1916

G. Scandens Unusual Stem Growth

"Diagram showing some types of unusual growth in thickness...C, portion of a cross section of stem of…

"Adianium pedatum: transverse section of stem, showing the amphiphloic siphonostele." -Stevens, 1916

A. Pedaium Stem

"Adianium pedatum: transverse section of stem, showing the amphiphloic siphonostele." -Stevens, 1916

The central part of the stem is the pith, then is the cellular tissue and finally the bark.

Woody Stem

The central part of the stem is the pith, then is the cellular tissue and finally the bark.

The central part of the stem is the pith, then is the cellular tissue and finally the bark.

Woody Stem

The central part of the stem is the pith, then is the cellular tissue and finally the bark.