Mosses and Lichens 



grottoes so that they fall upon the chlorophyll grains and enable 

 them by light-energy to build up plant foods from gases and 

 water. When searching for this moss one must be careful not 

 to intercept the rays of light which enter the cave and then one 

 may be fortunate enough to get the feebly reflected rays which 



VeiL 



Protonema in natural position, very highly magni- 

 fied. Illumination from above. 



Spore-case 

 with lid. 



Three cells of protonema from L to show position 

 of chlorophyll grains when the light rays enter per- 

 pendicular to the surface. 



Three cells of protonema to show position of chloro- 

 phyll grains when light rays enter obliquely. 

 Schistostega osmundacea 



Spore-case with 

 lid raised show- 

 ing spores. 



5. osmundacea. 



emerge from it. The four diagrams if taken in Older with their 

 legends, will give one a clear idea of how the light rays are 

 refracted and reflected by the cell-contents and of how the chlo- 

 rophyll grains move to that part of the cell which is illuminated. 



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