. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. REPRODUCTION, VEGETABLE (VEGETABLE OVUM). this manner it becomes firmly implanted, tlie tissue which surrounds it assuming the form of a sheath, and receiving the name of vagi- nnla. During this process, the dilated portion of the archegonium has increased in size, and has now attained about ten times its original length. Finally, it gives way at its line of junction with the vaginula, and is carried up- wards on the summit of the still lengthening fruit. 77. Development of the spores. — The upper portion of the cylindri
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. REPRODUCTION, VEGETABLE (VEGETABLE OVUM). this manner it becomes firmly implanted, tlie tissue which surrounds it assuming the form of a sheath, and receiving the name of vagi- nnla. During this process, the dilated portion of the archegonium has increased in size, and has now attained about ten times its original length. Finally, it gives way at its line of junction with the vaginula, and is carried up- wards on the summit of the still lengthening fruit. 77. Development of the spores. — The upper portion of the cylindrical fruit, which is des- tined to become the capsule, begins, some time after the calyptra has given way, to dilate rapidly. Soon after there is formed, by the separation of the external and superficial lay- Fig. Section of half-ripe fruit of the same, 50 diam. The globular dilatation exhibits the following parts: — a, the capsule. Within this, and separating it from the central portion, is a dark space, which corresponds to a cavity of the form of a hollow cylinder ; b, columella ; c, super- ficial layer of central portion; d, remains of archegonium; e, vaginula. (From fig. 164 to 166 from Hofmeister.) ers of cells from the central portion, a cavity of the form of a hollow cylinder, the axis of which coincides with that of the fruit. At this stage, the central portion consists of an axile column of large cells, closely invested by a single layer of smaller ones (the columella) ; a superficial layer of cells, about four times as large as those last mentioned ; and Lastly, between the two, a layer of nucleated cells, with granular contents, the primary parent cells of the spores. The development of these last consists in the disappearance of the nu- cleus of each, and the substitution for it of two others ; this being accompanied or fol- lowed by the division of the primordial mem- brane into two new vesicles, each of which encloses a nucleus. A cellulose membrane is
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