NATURE OF PLANTS 



113 



Returning now to the microspore, we find that its germination 

 also often begins while in its sporangium but in other cases 

 growth begins after it has escaped from the sporangium and has 

 been carried by the wind or some insect visiting the flower for 



Fig. 78. The germination of the. megaspore complete. The plant thus 

 formed consists of a female gamete or egg cell, 9 , below which are two syner- 

 gidae and in the center are the two uniting polar nuclei, p, while at the opposite 

 end of^^the sac are three antipodal cells, a; mi, micropyle; i, integuments; /, 

 stalk or funiculus in which a vascular bundle, v, has been developed to trans- 

 port food from the plant to the ovule. 



food, to the stigma of the pistil. The stigma is admirably 

 adapted to hold the microspores, being provided with minute out- 

 growths, and frequently sugary solutions are exuded which fasten 

 the spores to the stigma. The real importance of these sugary 

 solutions is to nourish the microspores. It is evident that these 

 minute dust-like cells can not contain sufficient food to bring 



