II 



MUSCINE^E—HEPA TIC/E—MA RCIIAN TIA LLS 



63 



are larger and more definite than those of the latter. At this 

 stage the cells hegin to separate by a partial deliquescence of 

 their cell walls, and when stained with Bismarck-brown these 

 mucilaginous walls colour very deeply, and the cells are very 

 distinct in sections so treated. They finally separate com- 

 pletely, and the much-enlarged globular capsule now contains 

 a mass of isolated cells of two kinds, globular sporogenous 

 cells and elongated elaters. The former now divide into four 

 spores, but before the nucleus divides the division of the spores 

 is indicated by ridges which project inward and (h'vide the 

 cavity of the mother cell much as in the Jungermanniacese. 



With the first divisions in the embryo the venter of the 



Fig. 25. — Fimhriaria Californica. A, Young, B, older embryo in median section. A, 

 X300; B, Xioo; C, upper part of a sporogonium, after the differentiation of the 

 archesporium, X200. 



archegonium, which before was only one cell thick, divides by 

 a series of periclinal walls into two layers of cells, which later 

 undergo further divisions, so that the calyptra surrounding the 

 older capsule may consist of four or more layers of cells. The 

 neck of the archegonium remains unchanged, but the tissue of 

 the thallus below the archegonium grows actively, and sur- 

 rounds the globular foot, which has grown down into the thallus 

 for some distance, and only the capsule remains within the 

 calyptra. This large growth of the foot is at the expense of 

 the surrounding cells of the thallus, which are destroyed by its 



