. The structure and development of mosses and ferns (Archegoniatae). that the antheridia are sunk in cham-bers, arranged in two rows, corresponding to the two seriesof segments of the apical cell. In the other thallose anacrogynous forms, c. g., Palla-vicinia (Fig. 41, A), the sexual organs are borne upon thedorsal surface of the ordinary shoots, usually surrounded bya sort of involucre. In most of these forms the apical cell isof a different type from that of Anciira, but is variable evenin the same species. Thus in Pallavicinia cylindrica, whilethe commoner form is nearly wedge-shaped, appea
. The structure and development of mosses and ferns (Archegoniatae). that the antheridia are sunk in cham-bers, arranged in two rows, corresponding to the two seriesof segments of the apical cell. In the other thallose anacrogynous forms, c. g., Palla-vicinia (Fig. 41, A), the sexual organs are borne upon thedorsal surface of the ordinary shoots, usually surrounded bya sort of involucre. In most of these forms the apical cell isof a different type from that of Anciira, but is variable evenin the same species. Thus in Pallavicinia cylindrica, whilethe commoner form is nearly wedge-shaped, appearing four-sided seen from the surface, and triangular in vertical section,it may approach very nearly the two-sided type (Fig. 42, C). 90 MOSSES AND FERNS CHAP. In the ordinary form four sets of segments are cut off,—dorsaland ventral, as in Riccia or Sphcerocarpus, and two sets oflateral ones. In Pellia calycina the apical cell shows a similarform, but in P. epiphylla (Fig. 42, D, E), another type isseen. Here, while the surface view is the same as in P. caly-. B. A
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Keywords: ., bookauthorcampbelldouglashought, bookcentury1900, bookdecade1910
