Fossombronia longiseta , Aust. 
IOI 
The Embryo. 
The first division in the embryo is transverse, dividing the con- 
siderably enlarged egg-cell into two nearly equal ones, Text-Fig. 8, A, the 
epibasal cell later giving rise to the capsule and seta as in the typical 
Jungermanniaceae, and the hypobasal portion giving rise to the rather 
conspicuous foot. Following the primary division there next occurs 
a transverse wall in the epibasal cell, dividing it into two, the uppermost 
evidently giving rise to the archesporium, and lower one the seta. 
There next occurs a third transverse division, this time dividing the 
epibasal cell into two, the lower one commonly dividing no further until 
Fig. 8. A-D. Successive stages in development of the embryo, x 560. E. Differentiation 
of archesporium and formation of first periclinal wall, x 560. F. A later stage in development 
of archesporium. x 560. G. An abnormal embryo, x 560. 
the embryo has reached an advanced stage, Text-Fig. 8, C. The embryo 
now consists of a tier of four superimposed cells, and the next division, 
Fig. 8, D, is a vertical one, followed by another at right angles to the first, 
thus dividing each cell into four parts. In the upper or archesporial cells 
are now formed periclinal walls, thus separating four archesporial cells 
from four wall-cells, Fig. 8, E, the initial layer of the capsule-wall. By 
this time a number of rather irregular divisions have occurred in the lower 
half of the embryo, along with an increase in size in the archesporial region, 
and, owing to the slow development of the stalk, the characteristic dumb- 
bell shape is already evident. 
