MOSSES AND FERNS 



CHAP. 



before the forking of the thallus, both of the new -growing 

 points continue to develop antheridia for a time, and the 

 receptacle has two branches in front corresponding to these. 

 The receptacle is covered with conspicuous papilla which 

 mark the cavities in which the antheridia are situated. Verti- 

 cal longitudinal sections through the young receptacle show 

 antheridia in all stages of development, as their formation, 

 like those of Riccia, is strictly acropetal. The first stages 

 are exactly like those of Riccia, and the primary cell divides 

 into two cells, a pedicel and the antheridium proper. The 

 divisions in the lower cell are somewhat irregular, but more 

 numerous than in Riccia, so that the stalk of the ripe anther- 

 idium is more massive (Fig. 14). In the upper cell a series 



Fig. 14. — Fimbriaria sp. (?). A, Part of a vertical section of a young antheridial receptacle, showing 

 two verj' young antheridia ((J), X420 ; B-E, older stages. 



of transverse walls is formed, varying in different species in 

 number, but more than in Riccia, and apparently always 

 perfectly horizontal. In MarcJiantia polymorpJia Strasburger^ 

 found as a rule but three cells, before the first vertical walls 

 were formed. In an undetermined species of Fimbriaria 

 (Fig. 14), much like F. Californica, the antheridia were un- 

 usually slender, and here frequently 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 and lowest cell of the body 

 of the antheridium, or the divisions in these parts are more 



^ Strasburger (2). 



