498 Campbell.— The Development of 
with the question of the affinities of Geothallus. The first 
division in the upper cell, instead of being transverse as in 
Sphaerocarpus , is vertical or oblique, agreeing thus with the 
typical Jungermanniaceae. In case the first wall is vertical, 
it is followed by two horizontal walls (Fig. 13), and each of 
the four cells is again divided by vertical walls so that regular 
octants are formed as in Sphaerocarpus. Where the first 
wall is strongly inclined (Fig. 14), the secondary wall is found 
first in the larger of the two cells, and the effect is produced 
of a two-sided apical cell like that found in the typical Moss- 
antheridium. A variation of this kind has been noted by the 
writer in Riccia 1 . Whether in any of these instances the 
regular octant-formation was suppressed could not be certainly 
determined ; but certain irregularities noticed in the cross- 
sections of the antheridium would indicate that this probably 
is sometimes the case. 
The next divisions are generally periclinal, and effect the 
separation of the central mass of cells, from which later the 
sperm-cells develop (Figs. 15, 16). These central cells soon 
acquire very dense contents, which stain strongly, and divide 
rapidly until the full number of sperm-cells is formed. These 
cells are arranged in groups corresponding to the primary 
divisions in the antheridium, and, especially where the contents 
have been slightly contracted through reagents (Fig. 17), show 
these primary divisions for a long time. The divisions occur 
mostly at right angles to each other, and the resulting sperm- 
cells, as so frequently happens in the Bryophytes, are nearly 
cubical. The nucleus of the sperm-cells is relatively large, 
but the sperm-cells themselves are smaller than is usual in 
the Jungermanniaceae. In this respect, and in the consequent 
small size of the spermatozoids, Geothallus recalls Riccia. 
Owing to their very small size, the spermatozoids do not offer 
a good subject for studying their development, and no attempt 
was made to follow this out. There was nothing to indicate 
any departure from the ordinary process. The free sperma- 
1 Campbell, Mosses and Ferns, p. 33. 
