I92 o] HAUPT—FOSSOMBRONIA 3 26 



The first wall of the initial is transverse, and comes in above 

 the general level of the thallus, resulting in the formation of a 

 basal cell and an outer cell (figs. 22-24). The former may undergo 

 another transverse division immediately, or it may remain undivided 

 until the 3 vertical walls have appeared in the outer cell (fig. 26). 

 The presence of 2 transverse walls in the young archegonium caused 

 the writer, during the early part of the investigation, to suspect that 

 possibly the first transverse division of the initial is followed by a 

 second one in the outer cell before the coming in of the 3 vertical 

 walls. Archegonia were seen, however, in which only one transverse 

 division of the initial had taken place (fig. 25), and the indications 

 were that the development of the archegonium may be typical, or 

 that the first 2 divisions of the archegonium initial may be the 

 same as the first 2 of the antheridium initial (fig. 10). 



Before the appearance of the first vertical wall, archegonia 

 cannot be distinguished from antheridia, and after the first vertical 

 wall has appeared the mitotic figure which would settle this point 

 has disappeared. In several cases, however, the wall in the basal 

 cell had not become thickened. This fact, together with the 

 general aspect and behavior of the neighboring cells of the thallus, 

 the position of the first wall in the initial, and the elongated 

 character of the undivided stalk cell, convinced the writer, after a 

 study of all available stages in the preparations, that the second 

 transverse wall comes in the basal cell and not in the outer cell. 



Subsequent development of the archegonium agrees with the 

 usual development of the archegonium of anacrogynous forms 

 (figs. 27-31). The cover cell divides by a median vertical wall 

 soon after its formation (fig. 29), and remains in this condition; 

 thus it does not contribute to the development of the neck, the 

 cells of which in all cases increase by intercalary divisions. The 

 mature archegonium has 6-8 neck canal cells, surrounded by 5 

 rows of neck cells (fig. 32). The venter is 2 cells in thickness, 

 and slender, and the neck but slightly twisted. The ventral 

 canal cell and egg are almost equal in size (fig. 31). After 

 the breaking down of the axial row the protoplast of the egg is 

 withdrawn somewhat from its wall, the very dense chromatin is 

 in close contact with the nucleolus, and elongated slender plastids 



