. Botany for high schools and colleges. Botany. 370 BOTANY. and is generally provided with root-hairs on its under sur- face, by means of which it secures nourishment for its inde- pendent growth (Fig. 253). In the RhizocarpecB the pro- thallium is so reduced as to be only a small outgrowth of the germinating spore. 4=86.—Both kinds of sexual organs usually occur upon the same prothallium. The antheridia consist of a few or many sperm-cells, which may or may not be surrounded by a wall. Fro. 253. Fig. 352.—A prothallium of a tern, seen from the under side, li, the root-hairs grow- ing from the
. Botany for high schools and colleges. Botany. 370 BOTANY. and is generally provided with root-hairs on its under sur- face, by means of which it secures nourishment for its inde- pendent growth (Fig. 253). In the RhizocarpecB the pro- thallium is so reduced as to be only a small outgrowth of the germinating spore. 4=86.—Both kinds of sexual organs usually occur upon the same prothallium. The antheridia consist of a few or many sperm-cells, which may or may not be surrounded by a wall. Fro. 253. Fig. 352.—A prothallium of a tern, seen from the under side, li, the root-hairs grow- ing from the basal end of the prothallium ; an, the antheridia scattered among the root-hairs ; ar, arcliegonia near the apex, x 10.—After Prantl. Pig. 853.—Mature antheridium of Adiantum CapUlus- Veneris, p, cells of prothal- lium ; a, wall of antheridium—the sperm-cells are seen escaping, in each a sperma- tozoid is coiled up ; 5, the spermatozoids ; 6, 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 prothallium ; one of the interior cells becomes divided into sperm-cells, in each of which is a spirally coiled spermatozoid (Fig. 353). In the other orders the antheridia are not confined to the under surface of the pro thallium j and in some of the RhizocarpecB 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 E. (Charles Edwin), 1845-1915. New York : H. Holt
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