. Our native ferns and their allies; with synoptical descriptions of the American Pteridophyta north of Mexico. Ferns; Pteridophyta. GERMINATIOISr OF FERN SPORES. 21 inent than the antheridia, consisting of an external layer of cells and a large central cell, which soon divides into two. The lower portion, at first the larger, develops into a roundish cell, which is analogous to the ovum among animals, and is called the oosphere. The upper portion of the central cell develops between those composing the neck of the archegonium into a canal filled with a sort of mucilage; this finally swells up
. Our native ferns and their allies; with synoptical descriptions of the American Pteridophyta north of Mexico. Ferns; Pteridophyta. GERMINATIOISr OF FERN SPORES. 21 inent than the antheridia, consisting of an external layer of cells and a large central cell, which soon divides into two. The lower portion, at first the larger, develops into a roundish cell, which is analogous to the ovum among animals, and is called the oosphere. The upper portion of the central cell develops between those composing the neck of the archegonium into a canal filled with a sort of mucilage; this finally swells up, forces the cells of the neck apart, and is expelled to aid in attracting. 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 Underwood, Lucien Marcus, 1853-1907. New York, H. Holt
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