. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. THE ANTHOCEROTES 149 (2) has also studied this species, and his results agree entirely with those of the writer. The thallus much resembles a small Anthoceros, and sec- tions through it show that in its growth and the development and structure of the sexual organs there is close correspondence. The thallus contains very large lacunae, which are formed in pretty regular acropetal order, and vertical sections show these large cavities increasing regularly in size as they recede from the apex. Si
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. THE ANTHOCEROTES 149 (2) has also studied this species, and his results agree entirely with those of the writer. The thallus much resembles a small Anthoceros, and sec- tions through it show that in its growth and the development and structure of the sexual organs there is close correspondence. The thallus contains very large lacunae, which are formed in pretty regular acropetal order, and vertical sections show these large cavities increasing regularly in size as they recede from the apex. Similar but less regular lacunae occur in A. fusifor- mis. The antheridia arise as in Anthoceros, endogenously. The youngest stage found is shown in Fig. 80, A. Here evi-. FxG. 80.—Notothylas orbicularis. Development of the antheridium. D, cross-section, the others longitudinal sections; E, nearly ripe antheridium, X300, the other fig- ures X600; (^, A, the primary antheridial cells. dently the young antheridia (<?) have been formed by the longi- tudinal division of a single hypodermal cell, whose sister epider- mal cell has divided again by a transverse wall to form the outer wall of the antheridial cavity (Figs. A, B). The commonest number of antheridia formed is four. Less regularity is found in the next divisions than in Antho- ceros, although in the main they are the same. This is observ- able both in longitudinal and cross-sections (see Fig. 80, D).. 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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