FERTILIZATION 87 



CHAPTER XIX 



FERTILIZATION 



WE all know that the fruit and seed follow the flower, and 

 as we go on to study the flower further, we see that every- 

 thing about it is constructed to favor the development of the 

 seed. Color, fragrance, position on the plant, time of open- 

 ing and shutting, the massing of flowers together ; in short, 

 every detail of structure to be found in any flower, is to help 

 in this work. 



We found in the ovary-cell certain ovules, which develop 

 into seeds under proper conditions. Let us consider one of 

 the most essential conditions to the development of the seed 

 from such ovules. 



Within the ovule there is no embryo at first, but there is, 

 among other things, a very small body, visible only under 

 the higher powers of the compound microscope, called the 

 nucleus. Within each little particle or grain of pollen there 

 is another microscopic nucleus. These two nuclei must 

 come together in the body of the ovule and unite into one 

 before the processes which result in the growth of an embryo 

 may be started. The process of accomplishing this is called 

 the fertilization of the flower. 



But in order that the nucleus from the pollen grain may 

 unite with that in the ovule, it must get over from the anther, 

 in some way, and down to the ovule itself; for the ovule 

 remains stationary, while the pollen grain is free to be 



