'342 PRACTICAL BOTANY 



5. The mature sporogonium or spore-capsule, of 

 which the head or theca is supported on a long stalk, 

 or seta. Note in specimens which are not too ripe 



a. The calyptra, a dry fibrous hood, covering 

 the apex of the sporogonium : beneath this is 



I. The lid-like operculum with its terminal beak : 

 this lid may be easily detached, disclosing 



c. The pale-grey epiphragm, which appears as a 

 transverse membrane, attached at its margin to the 

 capsule by a number of short teeth of the peristome. 



d. At the base of the theca observe a swelling called 

 the apophysis. 



e. By carefully removing the leaves from the apex of 

 a plant which bears a sporogonium, it may be seen 

 that the base of the seta is enveloped by a closely 

 fitting sheath, the veil or vaginula, the origin of which 

 will be explained later (page 350). 



Observation of the external characters of a simpler Moss, e.g. 

 Funaria hygrometrica, will give in the main similar results to 

 those above described for the larger Polytrichum. 



E. MICROSCOPIC INVESTIGATION 

 Oophyte Generation 



II. Cut transverse sections of a mature stem of 

 Polytrichum : mount some in glycerine, others in 

 chlor-zinc-iodine or in iodine solution : examine them 

 first under a low power, and observe in those mounted 

 in glycerine 



1. The outline of the section, which is usually more 

 or less clearly triangular. 



