THE 
HEW PHYTOIiOGIST. 
Vol. IX., No. 5 . 
May, 1910 . 
THE INTER-RELATIONSHIPS OF THE BRYOPHYTA, 
By F. Cavers, D.Sc. 
[Figs. 18-29.] 
MARCHANTIACE.E. 
HIS order (the “ Marchantiacese-Marchantioideac ” of Schiffner) 
1 is distinguished from all the lower groups of the Marchantiales 
by having stalked carpocephala. The thallus has (except in 
Dumortiera ) well-developed air chambers, which are either arranged 
in a single layer or are divided up by partitions so as to form several 
superposed series as seen in transverse section. When in a single 
layer the chambers contain assimilating filaments (except in the 
Astroporae). The pores on the thallus are either simple and 
surrounded by a single ring of cells or by several concentric rings, 
or are barrel-shaped. There are usually well-developed air chambers 
on the male and female receptacles, and these usually have the 
barrel type of pore. The antheridia are generally collected into a 
sharply defined cushion-like receptacle, which in the highest forms 
represents a branch-system, having several growing-points, and is 
then (except in Fegatella) stalked. The sporogonium is separable 
into foot, seta, and capsule; well-developed elaters are always 
present; the capsule opens by the separation of a more or less 
definite lid, or by splitting into several valves, or by both processes. 
The organisation of the carpocephalum, or archegoniophore, 
varies a good deal in the different members of the order. In the 
highest forms (Leitgeb’s “ Composite ”) there are two or more 
groups of archegonia, developed in centrifugal succession by as 
many radially arranged branches or growing apices. Owing to the 
more rapid growth of the upper tissue of the convex receptacle, the 
archegonia are carried on to the lower surface, and the youngest 
archegonia then stand nearest the stalk. The succession of the 
archegonia is, of course, acropetal with reference to each of the 
archegonium-producing growing-points and centrifugal with reference 
