Geothallus tuber osus , Campbell. 
497 
The Antheridium. 
There is a considerable variation in the form and size of the 
male plant, as well as in the number of antheridia produced. 
The thallus may remain unbranched (Fig. io), or it may fork 
once or twice. No definite relation between the young anthe- 
ridium and the segments of the apical cell could be discovered. 
As the young antheridia seldom stand exactly in the median 
line of the thallus, and are usually more or less inclined 
forward, exact median sections are not always easy to get ; 
but by cutting the thallus at different angles it was possible 
to obtain a series of slides which showed most of the 
different stages of development. 
The antheridium mother-cell (Fig. n) is very early dis- 
tinguishable from the neighbouring superficial cells of the 
thallus, and is formed further back from the apex than is the 
ease in Sphaerocarpus 1 . It is an elongated cell which projects 
strongly above the adjacent cells, and its nucleus is decidedly 
larger than the nuclei of the neighbouring cells. The proto- 
plasm is also denser, but the cell contains several large 
vacuoles. The first division-wall is horizontal, and nearly 
on a level with the surface of the thallus. This is followed 
by a similar division in the upper cell, dividing it into two 
of unequal size (Fig. 12). The original cell is thus divided 
into three superimposed cells, of which the basal one is coherent 
with the adjacent cells of the thallus, and the upper ones are 
free. Of the two upper cells, the lower smaller one forms the 
pedicel of the antheridium, the other its body. These first 
divisions correspond exactly to those in Sphaerocarpus ) and 
also in some other Liverworts. The basal cell divides usually 
by intersecting vertical walls, and forms a group of about 
four cells at the base of the antheridium, but takes no further 
part in its development. 
The subsequent divisions in the antheridium show con- 
siderable variation, and one of much interest in connexion 
1 Campbell, Mosses and Ferns, p. 79, Fig. 31, 
