136 MANUAL OF NATURB STUDY. 



i. e., in monoecious prothallia, two organs called 

 the antheridium and archegonium ; the former 

 answering to the stamens or anthers in the flower- 

 ing plant, and the latter to the pistil or ovary. 

 In other words, the antheridium is the male re- 

 productive organ of the plant, and the archego- 

 nium the female reproductive organ. As the 

 pollen-tube of the flowering plant must reach 

 the ovule for fertilization before the latter is ca- 

 pable of developtnent, even so must the energiz- 

 ing influence of the spermatozoid fertilize the ^%% 

 cell of the archegonium. Soon after this union, if 

 the weather is favorable, a young fern plant starts 

 out from the archegonium, and as soon as the fern 

 is firmly established the prothallium withers away. 

 The bean plantlet, you remember, draws its first 

 nourishment from the cotyledons or seed leaves, 

 and does not depend upon the soil until the 

 best part of the food in these leaves is used up. 

 The same may be said of beechnut or any flower- 

 ing plant. In the young corn plant the *albu- 

 men gives it the first start. Now the prothallium 

 of the fern answers that purpose precisely. Two 

 growing points start out from the archegonium at 

 the same time; one is the leaf point and the other 

 the root point; but the leaf point grows the faster, 

 obtainingits food from the prothallium. As soon as 



*The word endosperm is preferable. 



