62 MOSSES AND LIVERWORTS 



mentioned, grows almost everywhere, fruiting 

 most abundantly in April and May. The ring 

 is very susceptible to changes in the sur- 

 rounding air, and in particular to the presence 

 or absence of moisture; and so it happens that 

 when the spores are ripe, and the outside con- 

 ditions are favourable to their growth, it suddenly 

 rolls back, and in so doing will sometimes even 

 force off the lid, or at all events will so far 

 loosen it, that the next gust of wind may suffice 

 to completely remove it, and thus the spores are 

 in many cases free to escape. It will easily be 

 imagined that this ring of cells is extremely 

 minute, so minute indeed that it is hardly visible 

 unless considerably magnified. Fortunately in 

 the moss to which I have just referred it is 

 especially large and prominent, so that it is quite 

 possible with the help of a good magnifying- 

 glass and a fine dissecting-needle, and with the 

 exercise of some amount of care and patience, to 

 disentangle it from the mouth of the capsule, 

 and to lift it into the mounting medium, and thus 

 to obtain a very interesting microscopic slide. If 

 some of the capsules of this moss are examined 

 about the middle of May the unrolling of the ring 

 may be seen, a slight pressure on the cover-glass 

 often sufficing to bring this about. Plate VI. 

 fig. 2 is a drawing of a capsule in which the 

 ring has just uncoiled, as appears from the some- 

 what frayed or ragged appearance of the edge 



