HIDDEN MARRIAGES 



525 



patches of this moss a very noticeable feature of the heaths where it grows 

 in abundance, and often to a considerable height for a moss, that is. 



When the sporange is freed from the vagine and the calvpter, we 

 can see that it has a distinct lid or opercule, which is thrown off to allow 

 the escape of the spores. When this is lifted off, the sporange will be 

 found to have either a smooth rim around its mouth (gymnostomous), 

 or it bears a peristome a, single or double series of slender appendages', 

 the inner row being cilia, the outer row teeth, whose number is always 

 some multiple of four. The peristome is hygroscopic. When the atmo- 

 sphere is dry, the teeth or cilia stand away from the mouth and allow 

 the dispersion of the spores; in damp weather they close the orifice and 

 keep the spores dry. A very common species that exhibits this hygro- 



feffiM 



Photo by} [E. Step. 



FIG. 669. Two MOSSES. 



That to the left is the very common Cord Moss (Funaria hygrometrica) which comes up wherever vegetable matter 

 has been burnt on the ground. The clump to the right is the Convolute Screw Moss (Tortula convoluta). 



metrism well under a low power of the microscope is the Cord Moss 

 (Funaria hygrometrica) that forms a continuous carpet over the charred 

 earth wherever there has been a heath fire. A better example for those 

 who work with the pocket-lens rather than the compound microscope 

 will be found among the Screw Mosses (Tortula) that cover the tops of old 

 walls. One such is shown in fig. 664, where the comparatively long and 

 cylindrical capsules will be seen supported on long bristle-like stalks. The 

 teeth of the peristome are in this genus very long, and when closed they 

 are coiled spirally. The entire peristome then presents the appearance of 

 a reddish screw, which fact has suggested the name of Screw Moss. In 

 Polytrichum, in which the teeth are short, there is another piece of 

 mechanism to the same end. Beneath the opercule the mouth of the 



