434 



MOSSES AND FERNS 



CHAP. 



the cortical tissue strongly developed and full of starch. These 

 are supposed to survive long periods of drought, and to germi- 

 nate under favourable conditions. A condition somewhat 

 analogous to this appears in M. vestita (Fig. 243, A), but 

 whether these short lateral branches are of this nature was not 

 investigated. 



The Sporocarp (Sachs (i) ; Gochcl (6) ; Meunier (i) ; 



{Johnson (/, 2)) 



The development of the sporocarp is much the same in the 



I ^ 



/' . \^i -r^ \ 



coqo 



Fig. 254. — Pilularia Americana. Development of the sporocarp. A. \'ery young 

 sporophyll with sporocarp rudiment (sp), showing a distinct apical cell; B-D, 

 longitudinal sections of young stages, showing the formation of the "sorus canals" 

 (sc), X130; z', the original apex of the young sporocarp; L, secondary lobes or 

 leaflets; E, longitudinal section of an older stage, X about 130; s, s, young sori; 

 F, transverse section of an older sorus, X 180. 



two genera, but is most easily followed in the simple sporocarp 

 of Pilularia. In P. Americana, the young fruit begins to de- 

 velop almost as soon as the leaf can be recognised, and while it 

 is still close to the stem apex. Growth is stronger upon the 

 back of the young leaf, and it very early assumes the circinatc 



