14 PRACTICAL BOTANY. 



I. A layer of cells with peculiar thickening bands 

 on the inner and outer walls : these bands separate, 

 by rupture of the thinner parts of the walls, as the 

 inner and outer peristome, which thus consists 

 when mature of ribbands of cell-wall, and not of 

 complete cells. 



The above points may with advantage be confirmed 

 by observations on mature sporogonia. 



For comparison with the sections above described, transverse 

 and longitudinal sections may be cut from young sporogonia of 

 Funaria of various ages, and the development of this peculiar 

 organ may thus be traced. For details of description see the 

 text-books ; especially Goebel's Outlines, Eng. Ed., p. 186. 



XVI. Longitudinal and transverse sections may 

 also be made from the sporogonium of Polytrichum 

 commune, and this may be treated as above directed. 

 The chief differences from Funaria will be as 

 follows 



1. The clearly marked apophysis. 



2. The presence of two concentric air-spaces, 

 with the spore-sac between them. 



3. The more bulky operculum. 



4. The proportionately smaller peristome, consisting 

 in this case of bundles of prosenchymatous cells. 



5. The presence of an epiphragm, below the oper- 

 culum, and connecting the teeth of the peristome 

 temporarily together. 



6. The less clearly marked annulus. 



XVII. Scatter spores from the ripe sporogonium of 

 Funaria or Polytrichum over moist soil, and keep them 

 at a moderately high temperature, under a bell-glass, 

 for a few days. The surface of the soil will soon be seen 



