1915] HUTCHINSON— PELLIA EPIPHYLLA 137 



usual divisions." This character serves to emphasize the similarity 

 which exists between the archegonium as shown (figs. 31-33), and 

 the antheridium (figs. 16-21). Except for the position and pres- 

 ence or absence of the involucre, these organs would be difficult to 

 differentiate until the spermatogenous group or the archegonial 

 axial row, as the case may be, begins to develop. The cap cell 

 gives rise to a group consisting of more than the usual number 

 of cells. The first division of the cap is often simultaneous with 

 the division which gives rise to the primary neck canal cell and the 

 primary ventral cell (figs. 32, 35), and four cap cells may appear in 

 cross-section when there are but three neck canal cells and a ventral 

 cell (fig. 36). Fig. 38 shows a group of cap cells, 6 in cross-section, 

 which may be compared with those which form the neck of the 

 archegonium of Filicineae. Janczewski reports that the number 

 of neck canal cells may be as high as 16 or even 18; 9 is the greatest 

 number seen by the writer (fig. 38). The venter becomes massive 

 before fertilization; it may be 2 or 3 cells in thickness; a many- 

 celled stalk is also formed (fig. 37). In the young archegonium the 

 neck has usually only 5 vertical rows of cells. The cells originating 

 from the third wall cell do not divide until the archegonium ap- 

 proaches maturity (fig. 39). 



Methods of growth 



A certain form of apical cell may usually be given as character- 

 istic of a genus or even of a larger group. In P cilia, however, there 

 is no such conformity; the apical cell of P. calycina has four cutting 

 faces, two lateral, a dorsal, and a ventral — the cuneate apical cell. 

 The dolabrate apical cell of P. endivaefolia has but two cylindro- 

 convex cutting faces; while that reported as characteristic of P. 

 epiphylla, the lenticular cylindric apical cell, has a posterior convex 

 and two lateral cutting faces. In the last named species, however, 

 there are several methods of growth; these cannot be sharply 

 delimited, but for clearness five rather distinct forms may be taken 

 as characteristic of successive periods of growth. 



During the time of intra-capsular gametophytic division a 

 massive body is formed. There is no regional growth, but all cells 

 have an equal power of division. This period of growth is of short 



