. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. j/Lnfheridia of Equisetum, 300 dlam. a, ripe antheridium, from which the antherozoids are beginning to escape; b, unripe (Hofmeister.) the inferior surface, but along each margin of the principal branch of the prothallium. 88. Archcgonhun. — The archegonia were first discovered and figured by Milde * in Equisetum Telmateia, and have been since more completely described by Hofmeister-)-and BischoffJ in two other species. The pro- jecting papilliform portion consists, according to the last-mentioned observer
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. j/Lnfheridia of Equisetum, 300 dlam. a, ripe antheridium, from which the antherozoids are beginning to escape; b, unripe (Hofmeister.) the inferior surface, but along each margin of the principal branch of the prothallium. 88. Archcgonhun. — The archegonia were first discovered and figured by Milde * in Equisetum Telmateia, and have been since more completely described by Hofmeister-)-and BischoffJ in two other species. The pro- jecting papilliform portion consists, according to the last-mentioned observer, of eight cells, of which the four lower, in apposition to each other, have the general form of truncated cones, each presenting two flattened surfaces by which it is united to its two neighbours. The upper, in the same relation to each other, are nearly cylindrical, but are slightly rounded at their summits. The axis of the organ is occupied by a quadrilateral intercellular passage. The whole is supported on a base, which consists of two or three rows of cells Fig. superimposed upon each other, which com- bine to form a circular wall round a central cavity, which contains the germ, and is the termination of the quadrilateral canal. On the transformation of the germ-cell into the embryo, observations are as yet wanting. 89. Spores and sporangia.—The organs upon which the spore-cases are supported are ar- ranged in whorls round the upper part of the fruit-bearing stem. They seem to be modifications of the ordinary stem-leaves, on which account they have received the name of sporophylla. In its earliest condition, the sporophyllum is a cellular projection of the surface ; but, as it advances towards maturity, it assumes the form of a hexagonal disc Fig. 172. Archegonium of Equisetum Telmateia, 200 diam. The axial canal terminates in a spherical cavity, which is deeply embedded in the tissue of the prothallium, and contains the germ-cell (Bi- schoff.) * Zur Entwick. de
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