. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. LEPTOSPORANGIATM HETEROSPOREM 407 ing to Leitgeb/ the apical cell of the stem- is always three-sided at first, and only later attains its permanent form. The root remains undeveloped, and no later ones are produced, but the first divisions in what corresponds to the root quadrant in Azolla are apparently very similar to those of that plant, and it would perhaps be more correct to say that the primary root remains undeveloped rather than to consider it as completely absent (Dutailly (i)). The s

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. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. LEPTOSPORANGIATM HETEROSPOREM 407 ing to Leitgeb/ the apical cell of the stem- is always three-sided at first, and only later attains its permanent form. The root remains undeveloped, and no later ones are produced, but the first divisions in what corresponds to the root quadrant in Azolla are apparently very similar to those of that plant, and it would perhaps be more correct to say that the primary root remains undeveloped rather than to consider it as completely absent (Dutailly (i)). The second leaf in the embryo of Azolla arises practically from the first segment of the stem apex, and each subsequent segment also produces a leaf. The early growth in length of. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Campbell, Douglas Houghton, 1859-1953. New York, The Macmillan Company;

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