THE 
m PflYTOIiOGIST. 
Vol. IX., Nos. 8 & 9 . Oct. & Nov. 1910 . 
[Published November 25th]. 
THE INTER-RELATIONSHIPS OF THE BRYOPHYTA, 
By F. Cavers, D.Sc. 
[Figs. 44—54.] 
IV. ACROGYNOUS JUNGERMANNIALES. 
[ N the Acrogynae, the plant-body, or at any rate the portion of 
it which bears the sexual organs, is differentiated into stem 
and leaves. In some genera there is a thalloid ( Pteropsiella , 
Metzgeriopsis ) or even filamentous ( Protocephalozia ) phase in the 
life history of the sexual generation, but even in these cases the 
sexual organs are borne on leafy shoots. When archegonia are 
produced, whether on the main axis or on its branches, the apical 
cell itself is transformed into an archegonium, and the vegetative 
growth of the axis or branch is terminated. The leaves are 
developed in spiral succession from a three-sided (rarely two-sided) 
apical cell, and are arranged in two lateral rows, in addition to 
which there is often a ventral row of under-leaves, or amphigastria, 
frequently differing from the lateral ones in size and shape. 
The antheridia are borne in the axils of more or less modified 
leaves—“ male bracts ” or “ perigonial leaves.” The archegonia 
are usually surrounded by a special sheath, the “ perianth,” which 
arises as a ring-like outgrowth, when the archegonia are ripe, from 
the tissue immediately outside the group of archegonia; there 
is frequently, immediately outside the perianth, an “ involucre ” 
consisting of more or less modified leaves (“ female bracts ”). The 
antheridium is usually spherical, with a slender stalk ; the arche- 
gonium-neck consists of five rows of cells. The sporogonium is 
always differentiated into seta and capsule. The capsule opens 
by four valves, and elaters are always associated with the spores. 
