The Archegonium of Catharinea Angustata Brid. (Atrichum Angustatum)

Abstract

1. The archegonia of Catharinea angustata begin to develop in April. 2. The first formed archegonium arises from the apical cell region, but whether fron the apical cell itself or from one of its immediate segments must be determined later. 3. In the earlier stages of development the young archegonium is formed by the activity of an apical cell with two cutting faces producing a filament of a few cells. 4. The archegonium proper is initiated by the appearance in the terminal cell of 3 oblique walls cutting off 3 peripheral segments and originating the primary axial cell within, which on division gives rise to the cover cell and the central cell. 5. The central cell on division forms the primary neck canal cell and the ventral cell. 6. The cover cell is active for a time, cutting off peripheral segments for the outer cells of the neck and basal initials for the canal row. 7. The number of basal initials varies, but is at least 3 in Catharinea undulata. 8. The cells of the canal row and the peripheral cells of the neck grow by intercalary divisions, and in any order. 9. The major growth of the archegonium is intercalary. 10. The cells of the neck canal row have a double origin. The lower are formed by the intercalary divisions of the primary neck canal cell; the upper through the intercalary divisions of the 3 or more initials cut from the base of the cover cell. 11. The ventral cell divides relatively early into ventral canal cell and egg. 12. The ventral canal cell is variable in size. 13. The mature archegonium has usually more than 50 neck canal cells, and may contain as many as 86. 14. The canal row is generally multiple in its upper part and occasionally throughout. 15. The disintegration of the canal row is acropetal, but does not involve the ventral canal cell. 16. If the number of neck canal cells is an indication of primitiveness, the most advanced group of the mosses has the most primitive archegonium yet described among the Bryophyta.