i9"] CLAPP—ANEURA PINGUIS 185 



They contain plastids with starch. The protoplasts of the elaters 



* 



and spore mother cells are outlined by a definite membrane at a 

 distance from the wall. The space between, however, shows less 

 well defined strands. The nucleus of the elater is large (figs. 44, 

 45), at the center, extending well across the diameter of the cell. 

 There are plastids in the elaters, and Bolleter (2) considers the 

 elaters in Fegatella feeders of the spore mother cells because 

 the starch disappears from the elaterophore about this time. The 

 spore mother cells also have very large nuclei and the form of 

 the cell is irregularly rectangular to triangular. 



The difference in rate of growth noted before between the 

 peripheral and central regions is much more evident at this stage. 

 The four lobes of the spore mother cells are well rounded toward the 

 outer portions of the capsule, while those at the center are just 

 beginning to be distinct. The nucleus with a clear nucleolus lies 

 at the center of the lobed cell (fig. 46) . Two successive divisions 

 of the nucleus form the tetrad of spores. 



The cell plate becomes continuous with the deeply staining 

 membrane of the lobes. This membrane soon differentiates into 



another 



from the 



outline is very irregular. Centrally between the two margins 

 staining indicates lines of some substance which grow out to the 

 outer margin, forming at first irregular projections. Meanwhile, 

 within the protoplast a cellulose layer forms. When the spore is 

 mature the two wall layers are not distinct (figs. 51, 52). The 

 protoplast containing chloroplasts seems to be surrounded by a 

 single brown wall with echinate projections. During this time the 

 elaters have changed. The cytoplasm has come to form a spiral 



52). 



the wall and a broad brown thickening 



the elaters are often branched 



(Jack 14). Probably examination of the chemical changes taking 

 place in the spore coat would find them similar to those Beer (i) 

 has found for Riccia. 



The cell walls of the elaterophore are thickened in a narrow single 

 spiral. The two wall layers have ring thickenings in the sterile 

 cushion at the apex, and in the two upper layers of cells of the 

 seta irregular thickenings are found. The lines of dehiscence are 



