io8 
Cavers. — On the Structure and 
and closing of the pores. This is not the case with the pores on the 
thallus, which remain permanently open when similar experiments are tried. 
On the lower surface of the receptacle, immediately around the 
insertion of the stalk, there is a circular groove from the surface of which 
there spring numerous tuberculate rhizoids. Some of these rhizoids pass 
into a shallow groove on the anterior face of the stalk (PI. VII, Fig. 47). 
This groove is continuous with the ventral groove of the thallus, and the 
rhizoids traversing it become merged in the median bundle of the midrib. 
Many of the rhizoids springing from the receptacle remain outside of this 
groove and hang down over the surface of the stalk. 
The canal-cells of the mature archegonium become disorganized and 
converted into mucilage, and on the absorption of water the walls between 
these cells break down, the cover-cells being at the same time thrust 
aside and the mucilage being forced out of the open neck. The process of 
fertilization can be readily followed in Fegatella , owing to the comparatively 
large size of the antherozoids. A male plant with well-grown receptacles 
is kept dry for a few days, then a few drops of rain-water are placed on the 
upper surface of the receptacle ; on drawing the water off with a pipette, 
it is usually found to contain large numbers of swarming antherozoids. 
Longitudinal sections are then made through a female receptacle, the 
razor being kept dry. In most cases, one or more of these sections will be 
found to include a mature archegonium, and on mounting such a section in 
water, it is often possible to see the opening of the neck and the discharge 
of the canal-cells. On adding to such a preparation some of the water 
containing the antherozoids, the latter are seen to swarm around the open 
neck of the archegonium in large numbers, being evidently attracted 
by the extruded mucilage. Since the cells forming the archegonium neck 
and venter are usually fairly transparent, one can follow the passage of the 
antherozoids down the neck-canal. In some cases large numbers of anthero- 
zoids were seen to enter the canal, and when they reached the egg-cell they 
caused it to exhibit a rocking movement. Ultimately one of the antherozoids 
penetrates the egg-cell, whilst the others perish. 
Sporogonium (Fig. 32). 
The fertilized egg-cell secretes a cellulose wall around itself and then 
begins to grow and divide. The first wall is transverse (I), and it is some- 
times followed by a second transverse wall in the upper (epibasal) cell, but as 
a general rule the next walls are vertical and divide the embryo into regular 
octants (I, II). From the first, the embryo grows more vigorously in 
length than in breadth, and soon the lower (hypobasal) portion becomes 
separated from the upper by a constriction, the former giving rise to the foot, 
the latter to the stalk and capsule (VII). The foot becomes elongated and 
penetrates the compact tissue of the receptacle, the cells of which contain 
