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ut only when the sun is shining. They are visited by numerous insects which carry the pollen from one flower to another and deposit it upon the stigma, where it germinates, and the tube, growing down through the long style, finally reaches the ovules and fertilizes them. Usually only a comparatively small number of the seeds mature, there being almost always a number of imperfect ones in each pod. The pod or fruit (_F_) is full-grown about a month after the flower opens, and finally separates into three parts, and discharges the seeds. These are quite large (Fig. 81, _J_) and covered with a yellowish brown outer coat, and provided with a peculiar, whitish, spongy appendage attaching it to the placenta. A longitudinal section of a ripe seed (_K_) shows the very small, nearly triangular embryo (_em._), while the rest of the cavity of the seed is filled with a white, starch-bearing tissue, the endosperm. [Illustration: FIG. 82.--_Erythronium_. _A_, a portion of the wall of the anther, x 150. _B_, a single epidermal cell from the petal, x 150. _C_, cross-section of a fibro-vascular bundle of the stem, x 150. _tr._ vessels. _D_, _E_, longitudinal section of the same, showing the markings of the vessels, x 150. _F_, a bit of the epidermis from the lower surface of a leaf, showing the breathing pores, x 50. _G_, a single breathing pore, x 200. _H_, cross-section of a leaf, x 50. _st._ a breathing pore. _m_, the mesophyll. _fb._ a vein. _I_, cross-section of a breathing pore, x 200. _J_, young embryo, x 150.] A microscopical examination of the tissues of the plant shows them to be comparatively simple, this being especially the case with the fibro-vascular system. The epidermis of the leaf is readily removed, and examination shows it to be made up of oblong cells with large breathing pores in rows. The breathing pores are much larger than any we have yet seen, and are of the type common to most angiosperms. The ordinary epidermal cells are quite destitute of chlorophyll, but the two cells (guard cells) enclosing the breathing pore contain numerous chloroplasts, and the oblong nuclei of these cells are usually conspicuous (Fig. 82, _G_). By placing a piece of the leaf between pieces of pith, and making a number of thin cross-sections at right angles to the longer axis of the leaf, some of the breathing pores will probably be cut across, and their structure may be then better understood. Such
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