. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Development of parent cells of the spores of the same- a, one of the nucleated cells which constitute the central mass of the young sporangium; b, the central nucleus has disappeared, and is replaced by four others, one of which is out of focus; c, the cell is divided by six septa into four somewhat tetrahedral compartments. This ob- ject has by mistake been represented relatively smaller than the rest; d, the four compartments (special parent cells of the spores), are about to separate from each other: e, mature special
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Development of parent cells of the spores of the same- a, one of the nucleated cells which constitute the central mass of the young sporangium; b, the central nucleus has disappeared, and is replaced by four others, one of which is out of focus; c, the cell is divided by six septa into four somewhat tetrahedral compartments. This ob- ject has by mistake been represented relatively smaller than the rest; d, the four compartments (special parent cells of the spores), are about to separate from each other: e, mature special parent cell. In its interior we observe the nu- cleated spore, and between it and the membrane of the parent-cell, the coils of the two elastic fibres; f, the free spore ; the spiral fibres, which remain for a short time after its escape from the parent-cell, attached by their middle points to its membrane, have disappeared. cell, from which the gelatinous thickening has now disappeared. Soon after, springing asunder from each other, they tear the membrane of the parent cell, retaining, how- ever, their central attachment to the surface of the spore. 90. LycopocKacees.*—The large spore (ma- crospore) of Selaginella, consists, when ripe, of an internal spherical vesicle of delicate structure (endospore), which is enclosed in a resistant epispore. The endospore contains a fluid, in which float mucous and oleaginous granules only, its nucleus having disappeared. On its surface are observed three linear projections, all of which converge towards one point, the summit of the spore. The epispore, a structure of later formation, is composed of two layers, the internal of which is distinguished from the other by its remarkable transparency. The external sur- face is scattered over with acuminated projec- tions, which are connected with each other by a network of minute ridges. 91. The development of the prothallium commences (usually several months after the macrospore has been sow
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