so 



MOSSES AND FERNS 



CHAP. 



cell are somewhat irregular, but more numerous than in Riccia, 

 so that the stalk of the ripe antheridium is more rtiassive 

 (Fig. 1 6). In the upper cell a series of transverse walls is 

 formed, varying in different species in number, but more than 

 in Riccia, and apparently always perfectly horizontal. In 

 Marchantia polymorpha Strasburger (2) found as a rule but 

 three cells, before the first vertical walls were formed. In an 

 undetermined species of Fimhriaria (Fig. 15) probably F. 

 Bolanderi,- the antheridia wxre unusually slender, and fre- 

 quently four, and sometimes five transverse divisions are formed 

 before the first vertical walls appear. Sometimes all the cells 

 divide into equal quadrants by intersecting vertical walls, but 

 quite as often this division does not take place in the uppermost 



Fig. 15. — Fimbriaria sp. (?). A, Part of a vertical section of a young antheiidial 

 receptacle, showing two very young antheridia C^^), X420; B-E, older stages. 



and lowest cell of the body of the antheridium, or the divisions 

 in these parts are more irregular. The separation of the cen- 

 tral cells from the wall is exactly as in Riccia, and the lower 

 segments do not take any part in the formation of the sperm 

 cells, but remain as the basal part of the wall. In Fimbriaria 

 the top of the antheridium is prolonged as in Riccia, but in 

 Marchantia this is not the case. The wall cells, as the anther- 

 idium approaches maturity, are often much compressed, but 

 in Targionia hypophylla, where Leitgeb states that this com- 

 pression is so great that the cells appear like a simple membrane, 

 I found that, so far from this being the case, the cells were 

 extraordinarily large and distinct, and filled the whole space 

 between the body of the antheridium and the wall of the cavity, 

 which in Leitgeb's figures ((7), vi., PI. x., Fig. 12) is repre- 



