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 



