16^ 



THE ARCHEGONIUM. 



Only a very small number of the young archegonia were 

 found in 0. mohiccanum, and so no complete study of its 

 development was possible; but as the adult archegonium of 

 this species does not appear to differ materially from that 

 of 0. pendulum it is probable that its development is the 

 same as in the latter. The account given here is based 

 almost entirely upon a study of 0. pendulum of which a very 

 complete series of archegonia was secured. Lang figures 

 accurately several stages of the archegonium of this species, 

 and Bruchmann gives a series of figures illustrating the develop- 

 ment of the archegonium in 0. vidyatmn. The latter writer 

 failed to see the two nuclei of the neck canal cell which Lang 

 coiTectly figures for 0. pendidum. These two nuclei are invariably 

 present in both 0. pendidum and 0. mohiccanum, and they 

 presumably also occur in (9. vidgatum as they are constantly 

 present in Botrychium virginianum and in all of the true ferns 

 that have been accurately examined, as well as in Equisetum. 

 Neither Lang nor Bruchmann saw the ventral canal cell, which 

 is exceedingly difficult of demonstration. Jeffkky, however, 

 describes this in B. virginiamum, and it probably is always 

 present. 



As in the case of the antheridium, the youngest archegonia 

 may be found near the apex of the branch (Fig. 97), but may 

 also arise at a considerable distance back of it. In general, 

 like the antheridia, they arise in acropetal succession. 



The earliest stages closely resemble the corresponding ones 

 of the antheridium, and like the antheridium, the mother cell 

 is sometimes broad, sometimes narrow and deep, (Figs. 98, 99) 

 and the cover cell is correspondingly shallow or deep. Shortly 

 after the primary cover cell is formed the inner cell divides 

 into a central and a basal cell, as in the typical ferns. The 

 central cell as usual gives rise to the egg-cell and the canal cells. 



The next division is in the cover cell, which divides by a 

 vertical wall (Fig. 101) and almost immediately there is a 



