8o MOSSES AND FERNS chap. 



the capsule grows faster than the calyptra long before it is 

 mature, and the upper part of the calyptra is first compressed 

 very much and finally completely broken through by the en- 

 larging capsule. 



Leitgeb calls attention to the fact that soon after the 

 cells of the archesporium begin to separate, the whole mass 

 of cells becomes completely separated from the wall of the 

 capsule, which grows rapidly until the cavity w^ithin is much 

 larger than the group of archesporial cells, which thus float 

 free in the large cavity. Fig. 32, D shows a section through 

 a sporogonium at this stage. The cells making up the central 

 mass are apparently alike, but in the living sporogonium part 

 of the cells have abundant starch and chlorophyll, while in the 

 others these are wanting or present in much less quantity, 

 while their place is taken by oil, but no rule could be made 

 out as to the distribution of the two sorts of cells. The latter 

 are the spore mother cells, while the others are gradually used 

 up by the developing spores. The spores in S. terrestris remain 

 united in tetrads, and escape from the capsule by the gradual 

 decay of its wall and of the surrounding tissue of the gameto- 

 phyte. 



The male plants are very much smaller than the females, 

 with which they grow and under which they are at times 

 almost completely hidden. The cell walls of the antheridial 

 envelopes are often a dark purple-red colour, and this makes 

 them much harder to see than the vivid green female plant. 

 The apical growth and origin of the antheridium is the same 

 as in Riccia. The first division in the primary antheridial 

 cell is the same as in that of the archegonium, but the basal 

 cell is smaller, and does not divide again transversely, and 

 takes but little part in the formation of the stalk. In the an- 

 theridium mother cell are next formed two transverse walls, 

 dividing it into three superimposed cells. The two uppermost 

 divide, as in the Marchantiacese, by vertical median walls into 

 regular octants, the lower by a series of transverse walls into 

 the stalk, which consists of a single row of cells sunk below the 

 level of the thallus. After the division of the body of the 

 antheridium into the octant cells, periclinal Avails are formed 

 in each of these, so that the body of the antheridium consists 

 of eight central cells and eight peripheral ones, and the stalk 

 of two cells, of which the upper one forms the base of the 



