. Botany for high schools and colleges. Botany. 370 BOTANY. and is generally provided with root-liairs on its under sur- face, by means of whicli it secures nourishment for its inde- pendent growth (Fig. 252). In the RMzocarpem the pro- thallium is so reduced as to be only a small outgrowth of the germinating spore. 486.—Both kinds of sexual organs usually occur upon the same prothallinm. The antheridia consist of a few or many sperm-cells, which may or may not be surrounded by a wall. Fig. 252.—A prothallinm of a fern, seen from the under side, h, the root-hairs grow- ing from the basal end o
. Botany for high schools and colleges. Botany. 370 BOTANY. and is generally provided with root-liairs on its under sur- face, by means of whicli it secures nourishment for its inde- pendent growth (Fig. 252). In the RMzocarpem the pro- thallium is so reduced as to be only a small outgrowth of the germinating spore. 486.—Both kinds of sexual organs usually occur upon the same prothallinm. The antheridia consist of a few or many sperm-cells, which may or may not be surrounded by a wall. Fig. 252.—A prothallinm of a fern, seen from the under side, h, the root-hairs grow- ing from the basal end of the prothallinm ; an, the antheridia scattered among the root-hairs ; ar, archegonia near the apex, x 10.—After Prantl. Fig. 253.—Mature antheridium of ^c?mn^Mm Capillus-Veneris, p, cells of prothal- linm ; a, wall of antheridium—the sperm-cells are seen escaping, in each a sperma- tozoid is coiled up ; s, the spermatozoids ; b, the protoplasm of the sperm-cells still attached to the spermatozoids. x 550.—After Sachs. of other cells. In the Ferns (Filices) they are few-celled bodies, which project from the basal portion of the under surface of the prothallinm ; one of the interior cells becomes divided into sperm-cells, in each of which is a spirally coiled spermatozoid (Fig. 253). In the other orders the antheridia are not confined to the under surface of the prothallinm, and in some of the Rliizocarpece nearly the whole of the contents of a microspore is developed into one antheridium filled with 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 Bessey, Charles Edwin, 1845- [from old catalog]. New York, H. Holt and company
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