256 Field, Forest, and Wayside Flowers 



which is attractive but we do not yet know just 

 how or why to the spermatozoids. 



Some rainy day or dewy night, when the under 

 surface of the prothallus is wet, the active little 

 swimmers approach the open neck of the arche- 

 gonium, and are lured into it. And down in the 

 rounded part of the flask they find the "affinity" 

 which they have been unconsciously seeking, a 

 naked globe of colorless jelly known as the " oo- 

 sphere." One spermatozoid enters the oosphere, 

 and mingles with it, and with this act of fusion 

 the life-purpose of the prothallus is accomplished. 



The now fertilized oosphere surrounds itself with 

 a delicate membrane, and becomes the " oospore." 



So again in the life-history of the fern we have 

 come around to the single " cell" or globe of pro- 

 toplasm from which we can trace the development 

 of every living organism. 



From the first globe the fern-spore creative 

 Nature made the tiny heart-shaped prothallus. 

 From the second globe, the oospore, she will 

 make the perfect fern. 



A prothallus may form a number of archegonia 

 before a spermotozoid finds its way into any one 

 of them. But as soon as an archegonium is fer- 

 tilized no new ones appear, and the remaining life 



