266 



BRYOPHYTA 



styled an elaterophore. It is illustrated in the cases of Metzgeria and 

 Aneura (Fig. 127), and also in Pellia (Fig. 128). In the former the 

 elaterophore is attached internally at the distal end of the capsule, in the 

 latter at its base. In Aneura the capsule- wall consists of two layers of 

 cells, while the archesporium lies within. The differentiation of this body 

 is initiated early: in so young a sporogonium as that of Fig. 129 A 

 there is a distinction already marked by the protoplasmic contents between 

 a central group of more transparent cells and a peripheral band with 



FIG. 127. 



Aneura pinguis. Ripe capsule 

 in longitudinal section. From the 

 summit the elaterophore hangs into 

 the spore-cavity, in which are many 

 spores and elaters. Magnified. 

 (After Goebel.) 



FIG. 128. 



Pellia calycina. Sporo- 

 gonium opened, and emptied, 

 showing the valves of the 

 wall recurved, and an elatero- 

 phore of many threads. (After 

 Goebel.) 



denser protoplasm. The former constitutes only a central part of the 

 elaterophore : it is clearly shown at a later stage that the differentiation 

 has extended (Fig. 129 B), and that some of the inner products of the 

 darker band shown in Fig. A are also developing as sterile cells, while 

 it is only the fertile outer fringe which is the final residuum after these 

 progressive steps of sterilisation. This point comes out even more clearly 

 in a transverse section (Fig. 129 c), where the central group of cells 

 first differentiated are readily distinguished from those differentiated later. 

 There can be little doubt, after comparison with other Jungermanniaceae, 

 that the history of the individual development in this case gives a correct 



