PHYSIOLOGY OF TtiE CORN PLANT 



169 



nuclei is carried to the ovule and fuses with the nucleus 

 of the egg-cell. When this is done, fertilization is effected. 

 The fertilized egg then develops into the new individual or 

 embryo within the protecting coats of the' seed. The pro- 

 tecting coverings of the young seed were, before fertiliza- 

 tion, the coverings of the ovule. There is one silk for each 

 ovary and for any reason, should a portion of the silks 



Fig. 26. — Illustrating the process of fertiliza- 

 tion of the corn flower. ^ 



fail to receive pollen-grains, those ovules will not develop 

 and, the result will be an ear on which some grains are 

 lacking. It often happens in arid sections that dry 

 hot winds kill the pollen-grains and prevent the pro- 

 duction of grain, even though a vigorous stalk is pro- 

 duced. 



213. Double fertilization. — The process of fertiliza- 

 tion described above causes the development of only the 



