THE MOSSES 75 
the case of spores, like a cap of liberty. In the centre 
of the now inflated flask there is, amongst all mosses, a 
mass of tissue which does not itself form spores, but has 
its use as a storehouse of nourishment. Between this 
central mass and the lining a vast number of spores is 
forming and fattening upon the friendly tissue. When 
the time comes, the lid at the top springs open, and the 
spores are flung out. 
There is one interesting device on the part of many 
mosses which demands a moment’s attention. It is highly 
advisable that the spores should go out when it rains, so 
as to give them a chance of settling with a little moisture. 
As a device to secure this, many mosses are equipped 
with teeth about the aperture through which the spores 
must pass, and these teeth are very sensitive to damp, 
spreading open when they feel moisture in the air, and 
closing back upon the spores when it is too dry for 
them to have a fair chance. 
Such is the general life-history of a moss, of one, that 
is to say, which reproduces by spores. But do not forget 
that many mosses employ this method rather sparingly, 
and for the most part are content to spread in their own 
immediate neighbourhood by underground roots, or by 
the forming of young plants like themselves on their 
branches. 
The Sphagnum, or Bog-moss, for instance, is chiefly 
spread in this “vegetative” way, and that it has been 
fairly successful is shown by the fact that it forms an 
important element in the great deposits of peat which are 
to be found in various parts of the world. 
The Liverworts, the poor relations of the Mosses, are 
now a comparatively small group. Most of them have 
broad, flattened ribbon-like stems. which crawl over the 
