DEVELOPMENT. 



If longitudinal and transverse sections of the unripened 

 capsules of ^mosses, in various stages of growth, be cut for 

 microscopical examination,* these will form valuable aids 

 to the study of the growth and development of the capsule 

 and the spores. 



If a good section is made through a fully formed but 

 unripened capsule of Funaria, care being taken to choose a 

 nice, plump, green specimen, and this section be examined 

 with a power of about 140 dia- 

 meters or more, the structures to 

 be observed will be as follows : 



Beginning with the outer por- 

 tion of the section, there is first 

 a single layer of cells, forming 

 the outer wall of the capsule (fig. 

 9 /). These are thick- walled 

 cells, which become hardened as 

 the fruit ripens, are truly cuticu- 

 lar, and have occurring among 

 them at intervals stomata, similar 

 to those found on the cuticle of 

 the leaves of flowering plants. 

 These cells in ripening are often 

 deeply coloured, assuming in the 

 different species various shades 

 of brown, yellow, purple, at times 

 almost black, and in some cases 

 blood red. The next layer or 

 lining membrane of the capsule 

 is formed of two or more series 

 of large, thin-walled, spongy 

 cells, more or less filled with 

 the green chlorophyll granules. 



Next after this is the air cavity (fig. 9 ti). This air cavity 

 is intersected by numerous jointed alga-like cells, richly 

 charged with chlorophyll. These are attached to the lining 



y 



FIG. 9. Funariahygrometrica. 

 Longitudinal section of the theca 

 or capsule, bisecting it symme- 

 trically ; d, operculum ; a, an- 

 nulus ; c, columella ; h, air cavity; 

 s, the primary mother cells of the 

 spores ; f, outer wall of capsule ; 

 /, peristome, or fringe. 



* Directions for cutting these sections will be found in the last 

 chapter of this work. 



