AMERICAN JOURNAL OF BOTANY 
[Vol. io. 
156 
the gamete nuclei in fertilization. These preparations afford a favorable 
opportunity to trace in detail the development of the axial row which seems 
to be slightly different from that of any of the Hepaticae as yet described 
in complete detail. 
The stages preceding the division of the primary axial cell to form the 
cover cell and the mother cell of the axial row (terminology of Durand, 1908) 
have not been examined exhaustively, since these stages are not numerous 
in my preparations and since the cells in these stages are frequently shrunken 
somewhat by the action of the fixing reagents. Those cases observed seem 
to be in harmony with the general account of this development in the 
Hepaticae and with Miss Clapp’s account for this species. I have not 
attempted to trace the subsequent history of the cap cell, but such ob¬ 
servations as I have made seem to indicate that its behavior is so nearly like 
that of the other wall cells as to make it difficult to distinguish from them. 
The mother cell of the axial row grows somewhat before its first division 
into the central cell and the neck-canal mother cell (figs. 19-22, PI. XVII). 
These two cells grow to be relatively large before the next division, which 
occurs in the neck-canal mother cell (fig. 23) and leads to the formation 
of an axial row of three penultimate cells (fig. 24). Soon afterward the 
central cell divides, apparently equally, forming the egg and ventral canal 
cell (figs. 25-27). This division is followed by a period of growth, especially 
in the egg (fig. 28). Archegonia at this stage of development are fairly 
frequent in my preparations. Later the penultimate cell next above the 
ventral canal cell divides (figs. 29, 30, 38, PI. XVIII); this division being 
followed shortly by a division of the uppermost of the penultimate cells 
of the axial row (figs. 30, 31). The final result is an axial row of six cells— 
egg, ventral canal cell, and four neck-canal cells. The last two divisions are 
not frequent in my preparations, and I have not been able to determine 
whether cell division follows nuclear division in all cases as it seems to in 
the penultimate cell next above the ventral canal cell shown in figures 29, 
30, and 38, followed very soon by a disappearance of the division membrane, 
or whether the division of the cell may be omitted, as is suggested by such 
conditions as are represented in figure 31, Plate XVIII, and figures 42 and 43, 
Plate XIX. Durand (1908) finds that in Marchantia the nuclei of the neck- 
canal cells sometimes divide just before the disintegration of these cells, 
these nuclear divisions not being followed by cell divisions. The scarcity 
of archegonia showing the ultimate cells of the neck-canal row is probably 
accounted for by the short duration of these cells (Clapp, 1912; Florin, 1918). 
I have been unable to detect a cell wall between any two of the cells 
of the axial row, except usually a thin film between the egg and the ventral 
canal cell. This film seems to be continuous with the walls of the cells 
of the venter (fig. 27, PI. XVII; figs. 32, 34, 35, PI. XVIII) and stains (with 
light green) like a cell wall. In disintegrating, the protoplasts of the canal 
cells probably form a hydrophilous colloidal mass which by its swelling 
forces open the end of the neck (fig. 33, PI. XVIII; figs. 39, 40, PI. XIX). 
