148 THE FLOWERING PLANT. 
about in all directions, and ultimately some of them are 
attracted to the archegonia. Fertilization (in this case cross- 
fertilization, p. 115) consists in the fusion with the egg-cell of 
an antherozoid which has wriggled through the mucilage in the 
neck of the archegonium. 
The fertilized egg-cell, now termed the odspore, divides into 
a small mass of cells which begins to grow upwards, and ulti- 
mately becomes the spore-capsule. ‘The archegonium goes on 
growing as the spore-capsule develops within it, but after a time 
it is no longer able to grow quickly enough, and finally ruptures, 
part of it being carried up on the tip of the capsule as the 
calyptra. 
The life-history of the moss, consisting as it does of a spore- 
producing stage and an egg-cell-producing stage, is a good 
example of the phenomenon known as alternation of genera- 
tions. In bryophytes the dominant stage is the odphyte, and 
upon it the sporophyte lives in a parasitic manner (cp. p. 3). 
The moss odphyte is not only able to produce sporophytes by 
means of fertilized egg-cells, but is also capable of giving rise to 
fresh odphytes by vegetative reproduction of various kinds, and 
this is why such large numbers of plants are commonly found 
growing together. The following diagram will serve to repre- 
sent the successive stages in the life-history. 
SPOROPHYTE 
Spore-capsule 
a 
spore oospore 
1 ve ane 
ae ege-cell antherozoid 
es archegonium antheridium 
eee Le 
. > 
Moss Plant 
OOPHYTE 
Mosses differ from one another in various particulars, though they 
agree in essentials with the foregoing description. As to the oéphytes, 
there is considerable difference in the arrangement of the archegonia 
and antheridia, which may grow together on the same plant, and even 
