203 
Lemaneaceae of the United States. 
The section is fortunate in presenting a ray b 8 which bears 
four generative filaments e e 1 e 2 and e 3 , and a tie-cell c ; the 
other ray-cell b bears three generative filaments, / ascending 
and e 5 e G descending, and no tie-cell. In this half of the sexual 
segment the normal number of generative filaments is three 
ascending at their origin on the ray-cells, e 2 e 3 and £ 4 , and 
four descending, e e 1 e 5 and e 6 ; but the normal number of 
ascending filaments becomes four by the branching of the first 
cell e 2 , forming h and h 1 ; g g 1 g 2 are redundant ones from 
the normal one e*, formed by the growth of it's primary tie- 
cell on that side ; / is a redundant one arising from a descend- 
ing one, e 6 , by an extension of the middle tie-cell of the first 
cell of the filament. Nearly all ,pf the primary tie-cells 
possess secondary tie-cells, which connect them with the wall. 
In many cases the secondary tie-cell, which lies in the direc- 
tion of the antherid-zone, is continued into a short redundant 
filament. Many of these redundant generative filaments 
function as normal ones by producing antheridia. On e, k l is 
the first tie-cell which forms a fertile redundant generative 
filament. The next one arises from the next cell on the op- 
posite side, k 2 ; h 5 the next one on the opposite side of the 
next cell ; k 4 the normal one now continues simple to the 
antherid-zone, while k G forms by alternate tie-cells k G and k G ; 
k 1 and k 8 being a continuation of k 5 . 
The primary tie-cells are usually three for each cell of the 
generative filament, two lateral and one directly between the 
cell and the wall. According to the distance of the generative 
filaments from the wall, the tie-cells are long or short, clavate 
or pyriform. 
After this study of the development of a primary mother- 
cell of the young sexual shoot into a sexually mature segment 
of the ripe sexual shoot, the appropriateness of the term seg- 
ment, or sexual segment, becomes more apparent, since it is 
a structural and biological unit. 
4. Development of the Organs of Reproduction. Antheridia. 
The antheridia arise from specialized cells which terminate 
the generative filaments, either normal or redundant. Fig. 
