THE MOSSES 71 
almost any part of the plant, if cut or torn away, can 
reproduce another plant with ease. Their stems run 
underground, throw up a new shoot, and wither away 
when it is established; small plants are formed on the 
moss plant itself, and drop off when fully fledged, and 
fragments carried off by rain or wind to suitable soils 
speedily establish themselves afresh. 
The spore-reproduction, however, is a more complex 
business, and we now come to a fact in vegetable life 
which needs your careful attention. This fact is known 
as the “Alternation of Generations.” Put quite briefly, 
and therefore with only rough accuracy, mosses don’t 
have children at all like themselves, but only grand- © 
children! It is not the same transformation as that 
of a caterpillar into a butterfly, for the plant in one 
stage may go on for a long time producing plants in 
the next; but a nearer parallel, though not one to be 
followed too closely, would be if the children of horses 
were donkeys, and of donkeys, horses, 
In one generation of mosses we find two kinds of 
organs for reproduction, which have to combine by some 
means or other; the details of the process we shall go 
through later. When they have combined, a new plant 
is produced, which commences to grow independently, 
though not breaking away entirely. Within this new 
plant, which does not look at all like its parent, spores 
are formed, without the assistance of any double set of 
cells, to an enormous number, and these are spread 
abroad to grow up into new plants, each with its double 
set of reproducing cells. The first plant, with its male 
and female organs, is known as the sexual generation; the 
second, which produces spores, as the asexual generation. 
To bring this out rather more clearly, let us go through 
