32 HOFMEISTER, ON 



the same thickness as before. The archegonia, consequently, 

 appear to be seated upon the scarp produced on the upper 

 surface by the sudden diminution in thickness of the joint 

 of the stem (PI. V, fig. 1). The development and struc- 

 ture of their first rudiments correspond exactly to those of 

 the very young antheridia. A cell of the upper surface of 

 the yet very young shoot becomes slightly arched outwards ; 

 it divides by a septum inclined to the surface of the stem, 

 and the upper one of the newly formed cells divides by a 

 septum inclined in an opposite direction to the latter septum. 

 Whilst the division is repeated in the new terminal cell by a 

 septum perpendicular to the last and parallel to the last but 

 one, the last formed joint-cell divides by a vertical septum 

 into two cells whose basal outline is a quadrant. The 

 same process recurs in each second-youngest cell, whilst 

 the terminal cell divides anew by a septum inclined in a 

 direction opposite to that of the last. The archegonium 

 would have the appearance of a column consisting of 

 four rows of cells, but for the fact that in all the cells 

 of one of the four rows, immediately after the division 

 of the cell of the second order by a radial longitudinal 

 septum, a partition-wall appears which divides the cell into 

 an inner three-sided cell, surrounded by other cells, and an 

 outer cell, of which one of the four walls is free (PI. V, 

 figs. 3, 4). The young archegonium thus presents the ap- 

 pearance of a cylinder of cellular tissue, rounded above, con- 

 sisting of a central string of cells (as many as thirty in 

 number), which is surrounded by a single layer of four 

 cells. The central cellular string does not extend quite to 

 the base of the young archegonium, which base consists of 

 a short stalk, of the height of one or two cells, and com- 

 posed of four cells lying in the same plane (PL V, figs. 5, 

 G, 6*). The cells of the central string become filled, soon 

 after their formation, with a granular mucilage, in which 

 the nucleus lies imbedded in the form of a transparent 

 vesicle (PI. V, fig. 4). The undermost of those cells swells 

 considerably ; its nucleus also increases in size (PI. V, 

 fig. 5). The adjoining cells divide by longitudinal septa 

 as soon as the longitudinal growth of the archegonium is 

 finished (PI. V, figs. 5, 6, 7). The same division proceeds 



