. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Antherldia of Griffithsia, 30 diam. a, a kind of involucre is formed by a whorl of six verticillate branchlets, at the points of bifurcation of each of which is borne an antheridium; b, terminal tuft from surface of antheridium, along with a few of the hyaline vesicles, 300 diam. (Thuret). formed of larger cells placed end to end. At the junctions of these, smaller branches are given out, upon which the hyaline cells are sessile. These last possess a diameter of about yJ^ of an inch. From the above details it will be see
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Antherldia of Griffithsia, 30 diam. a, a kind of involucre is formed by a whorl of six verticillate branchlets, at the points of bifurcation of each of which is borne an antheridium; b, terminal tuft from surface of antheridium, along with a few of the hyaline vesicles, 300 diam. (Thuret). formed of larger cells placed end to end. At the junctions of these, smaller branches are given out, upon which the hyaline cells are sessile. These last possess a diameter of about yJ^ of an inch. From the above details it will be seen that great difficulties lie in the way of a comparison between the reproductive organs of the Flo- rideas and those of other families. Nageli considers them to present a strong analogy with those of the Hepaticae, with which he places the Florideae in a parallel position. We shall see, as we advance, how little ground there is for such a view. The Florideae are trioecious plants : the tetraspores, polyspores, and antheridia being never found together in one individual. 24. CharacecE. — Although we are well ac- quainted with the structure of the reproductive organs of the Characea?, we are, as yet, able to perceive only subordinate relations between them and those of other plants. These organs are of two kinds; the one being destined to the production of a germ, the other to that of antherozoids. The former is an oblong oval body, which is placed at the junction of two segments of the articulate tubular stem. It consists of an oval germ-cell, invested by two envelopes. The outer of these is remarkable for the arrangement of the five tubular cells of which it is formed, which are twisted spirally round the central parts, and form by their ends, at the summit, a crown of five teeth. The germination of Chara has been ob- served and described by Vaucber.* The de- velopment of the germ, which ripens in autumn, does not take place until spring. It * Yaucher, Mem. Soc. Hist. Nat.
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