Fossombronia longiseta , A test. 93 
dividing vertically to form the antheridium, while the basal cell, by a series 
of transverse walls, forms the foot. 
In Fossombronia the development thus far agrees exactly with that in 
Sphaerocarpus and Geothallus , except that in Fossombronia only one hori- 
zontal division occurs in the antheridium-mother-cell, the stalk arising from 
the basal cell formed by the first horizontal division. This basal cell later 
divides horizontally, the uppermost segment becoming active in the forma- 
tion of the stalk, while the lower ordinarily does not divide again. Following 
the horizontal division of the antheridium-mother-cell are two vertical 
Fig. 6. A. Longitudinal section of a young antheridium. x 560. B. Cross-section of one 
about the same age. x 560. C. Cross-section of a nearly mature antheridium, primary divisions 
still evident, x 560. 
divisions forming planes at right angles to each other and dividing the 
antheridium into octants (Figs. 5 and 6, PI. V). The next division 
results in periclinal walls for each of these octants, and there thus arise eight 
central cells and eight periclinal ones. The resulting divisions of the octant 
cells occur with considerable regularity, developing sperm-cells which are 
nearly perfect cubes. The primary divisions remain visible up to the early 
stages of spermatogenesis. Judging from the development of the anther- 
idium, Fossombronia is more closely related to Sphaerocarpus and Geothallus 
than to the higher forms of the J ungermanniaceae. Leitgeb 1 , in his 
1 loc. cit. , Heft 3, p. 1 1 2, 
