36 A HALF-HOUR WITH THE 



We therefore proceed to describe the spore-bearing 

 organ. This may be easily seen with the naked 

 eye, although its beauties cannot be brought fully 

 out without the aid of the Microscope. The part 

 which contains the spores is seated on a little stalk, 

 and is called the " urn " (Fig. 110% PL 4). Cover- 

 ing the urn, and fitting on to it like a nightcap, 

 is the calyptra (a). On slipping off the calyptra, 

 a conical body fitting into the urn is observed, and 

 this is called the " operculum" (6). If the operculum 

 is now lifted off, there is revealed, below, a series of 

 twisted hair-like threads (c), which are called the 

 " peristome." These processes are held together by 

 minute teeth (d). The spores (e) are found in the 

 interior of the urn. All these parts are subject to 

 great varieties in different kinds of mosses. 



From the mosses we may pass on to the ferns. 

 Like the mosses, they have no regular flowers, and 

 the parts which correspond to the urns of the 

 mosses are the small brown scaly-looking bodies 

 seated on the back of the fronds, or leaves. In the 

 male fern the little brown bodies which contain 

 the spores are round (Fig. Ill, PJ. 4), and in the 

 common brakes they are placed on the edge of the 

 fronds (Fig. 112, PI. 4). These organs, which are 

 called "sori," may be easily seen as opaque objects, 

 under the lower powers of the Microscope. In the 

 common hart's-tongue, or scolopendrum, the sori are 

 arranged in elongated bands. In this case the sori 

 are covered with a membrane called an " indusium." 

 On opening this, the sori are found lying close toge- 

 ther. Each one of these sori is found to be made 

 up of a number of cases called capsules, or " thecse," 

 attached to a stalk by which they are fixed to the 

 frond (Fig. 113, PL 4). These thecse are beautiful 

 objects under the Microscope. Springing from the 

 top of the stalk is a series of cells which surround 



