The Sporing of the Fern 259 
plish one purpose,—that this purpose is the fusion 
of two reproductive cells, one male and the other 
female,—and that when this life-work is finished it 
dies. And as the unfertilized flower lives long past 
its normal time of blooming, still waiting for breeze 
or insect to bring it pollen wherewith to set its 
seed, the unfertilized prothallus may continue to 
grow for several months, or even, in the case of 
the Osmunda, for years. 
But as soon as spermatozoids have entered the 
archegonia, and one or two oospores have been 
formed, the prothallus begins to wither. 
The oospore is soon cut into two parts by a 
vertical partition, and then into four by a horizon- 
tal one. Three of these divisions become the stem, 
leaf and first root of the young fern. The fourth 
becomes an organ termed ‘‘ the foot’’ by means of 
which the fern draws its support from the parent 
prothallus till it is old enough to shift for itself. 
By that time the prothallus is quite depleted and 
exhausted. 
After the fern has passed its earliest youth the 
first-formed or ‘‘ primary’’ root withers away. 
In most native species the main stem lies hori- 
zontally along the surface of the earth, or just 
beneath it. The leaves or ‘‘fronds’’ spring from 
