The Origin of the Archegonium \ 
BY 
BRADLEY MOORE DAVIS. 
With two Figures in the Text. 
HE gap between the Thallophytes and those groups of 
-L higher plants which may collectively be called the 
Archegoniates is perhaps the most difficult of all to bridge 
when one attempts to trace the evolution of the plant king- 
dom. The problems chiefly concern the relation of the sexual 
organs in the two groups, or more precisely the origin of the 
archegonium and antheridium of the Bryophytes. 
The presence of a well-defined sporophyte generation in 
the Bryophytes, while an important distinguishing character, 
gives less difficulty, because studies among the Thallophytes 
in recent years have indicated the possibility of a very general 
tendency towards the development of a sporophyte in this 
group. It is probably shown at low levels of the Confervales 
(Ulothrix ) , in the Conjugales and the Oedogoniaceae, while 
Coleochaete , the Rhodophyceae, and perhaps the Ascomy- 
cetes, present sporophyte generations that in complexity may 
fairly be compared with the simplest Bryophytes. 
But the archegonium and antheridium have no parallel in 
the sexual organs of the higher Thallophytes, i. e. those groups 
1 Contributions from the Hull Botanical Laboratory, No, 48. 
[Annals of Botany, Vol. XVII. No. LXVII. June, 1903.] 
