66 WONDERS OF PLANT LIFE 



typical case may be briefly outlined. Being very 

 light, the spores float away on the slightest breezes 

 and a certain number of them are sure to find 

 a resting-place on some moist patch of soil. It 

 is not very long after the lodgment of the 

 spores that a change takes place, which by a 

 process of cell extension results in the pro- 

 duction of a heart-shaped green film in measure- 

 ment about an eighth of an inch known as 

 the prothallium. After an interval, two very 

 distinct kinds of cells begin to put in an appear- 

 ance upon the under-side of the prothallium. 

 These represent respectively the archegonia, or 

 germ cell, and the antheridia, or sperm cell. At 

 a certain stage in the history of these cells, thread- 

 like processes, known as antherozoids, emerge 

 from the sperm cells and enter the germ cells, and 

 thus bring about the fertilisation of the embryo. 

 Soon after this has been accomplished the pro- 

 thallium and all its system of cells dries up, leaving 

 behind only the fecundated germ. Yet another 

 change, and the tiny frond struggles upwards, 

 and the birth of the Fern is an accomplished fact. 



