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Hattdhook of Nature-Study 



masses of tiny globules, not larger than pin points, push out from beneath 

 the margin of these dots. The blisterlike membrane is simply a cover for 

 the growing spores, and is called the indusium; by July it shrivels into an 

 irregular scroll, still clinging to the pinnule by its depressed center; and 



by this time the profu- 

 sion of tiny globules 

 covers the entire under 

 side of the pinna like 

 a brown fuzz. If we 

 scrape off some of this 

 fuzz and examine it with 

 a lens, we can see that it 

 consists of numberless 

 little globules, each with 

 a stem to attach it to the 

 leaf; these are the spore- 

 cases, or sporangia, each 

 globule being packed full 

 of spores which, even 

 through the lens, look 

 like yellowish powder. 

 But each particle of this 

 dust has its own structure and contains in its heart the living fern-sub- 

 stance. 



Not all the fronds of the fern clump bear these fruit-dots. The ones 

 we select for decoration are usually the sterile fronds, for the fertile ones 

 are not so graceful, and many ignorant people think the brown spore-cases 

 are a fungus. The Christmas fern being evergreen and very firm in tex- 



/. Fertile leaflet of Christmas fern showing indusia 

 and spore-cases. 2. An indusium and spore-cases, en- 

 larged. J. A spore-case, enlarged. 4. A spore-case 

 discharging spores, enlarged. 



The common polypody often mistaken for the Christmas fern. 

 Photo by Verne Morton. 



