Lemaneaceae of the United States. 199 
the ray-cell (Fig. 7 e ) ; at other times the descending genera- 
tive filament is marked off first, or at the same time. Again, 
an oblique line of fission may first mark off one of the ascend- 
ing generative filaments. There is no regular succession 
which is invariable, but the fission finally results in the four 
daughter-cells (Fig. 7 g, the group of cells at the right). 
The ray-cell now elongates perpendicularly to the central 
axis, and the outer end, by peripheral fission, produces tie- 
cells, and by growth in the direction of the generative fila- 
ments forms the T- or L-cell. Each primary cell of the 
generative filaments, by peripheral and radial fission, produces 
the tie-cells, and by longitudinal growth and transverse fission 
produces another cell of the generative filament. This process 
is repeated together with the branching of the generative fila- 
ments until the antherid-zone is reached. An examination of 
Fig- 7 will show how the several first steps of the process pro- 
ceed. The young sexual shoot, treated with potassium 
hydrate and then stained with eosin, contracts the young 
sexual segments and the product of fission of the four original 
peripheral cells into well-defined groups. 
Subgenus Lemanea. Upon the character of fission of the 
mother-cells of the ray-cells and generative filaments depends 
the presence or absence of a tie-cell, which connects the ray- 
cell directly with the wall. The absence of this tie-cell usually 
occurs at the ray- cell which bears only one ascending and two 
descending generative filaments. The smaller cell (Fig. 29 c , 
the middle cell) is the mother-cell of these. It usually divides 
first into four cells in such a manner as to leave an inner 
pyramidal cell with a broad base resting against the cell of 
the central axis, and the apex short of the periphery of the 
mother-cell. The remaining cells are the primary cells of the 
one ascending and two descending generative filaments. (See 
Fig. 29 the central group of cells ; the ray-cell cannot be 
seen in the illustration.) The ray-cell now merely elongates : 
it does not divide again, so that no tie-cell connects it directly 
with the wall. The larger mother-cell usually divides into five 
daughter-cells in such a manner as to leave a middle cell shaped 
