FERNS. 



l6 5 



after the dispersal of the spores; for material which has been 

 dried for nearly twenty years has been used to show the 

 snapping of the sporangium. The sporangia which remain on 

 the leaves out-doors snap so often with the changes of the 

 weather that the annulus is literally worn out. 



Synopsis. 



f Root. 

 Stem. 



Fern plant. - 



Leaf. ■ 



Sterile leaves. 



Petiole. 



Lamina, 

 f Petiole. 



Fertile leaves, i.e., 



spore-bearing 



leaves. 



Lamina. ' 



' Fruit dots (sorus). 

 Indusium when 

 present. 

 Sporangium. 

 Spores. 



material and apparatus. — Entire plants with the root stock, and some of 

 the leaves with the fruit dots, may be preserved dry. 



Portions of the leaves with the fruit dots, at the time the spores have just 

 matured, but have not opened, may be preserved in 2% formalin. If possi- 

 ble, for the study of the opening of the sporangia obtain fresh material of 

 the mature sporangia. They may often be obtained from greenhouses, and 

 the leaf with the fruit dots before the sporangia have opened should be im- 

 mersed in water as they are taken to the laboratory or in a very damp moist 

 :hamber, since the dry air of the room soon causes them to open and scatter 

 the spores. 



Apparatus, the same as in Chapter XXIV. 



Glycerine. 



