PTERIDOPHTTA. 



221 



(oosphere). Fertilization takes place in water (after rains 

 or heavy dews), the antherozoids swimming to and down 



Fig. 129.— Antherids of a fern (Polypodium vulgare), X 240. A, at ma- 

 turity ; B, empty ; C, antherozoids of same, X 540. (From Strasburger.) 



Fig. 130.— Archegonea of a fern (Polypodium vulgare), X 240. A, Deiore, 

 B, after, opening. (From Strasburger.) 



the neck of the archegone, where they unite with the 

 germ-cell. 



412. After fertilization the germ-cell divides again and 

 again, soon producing a short stem from which a root 

 springs at one end, while from the other the leaves arise. 

 The latter are at first small and quite simple in structure, 

 but those formed later are larger and more and more com- 



