124 DOMESTICATED ANIMALS AND PLANTS 



It will be found that the characteristic thing which normally 

 happens is this : one of the little particles of yellow dust drops 

 upon the sticky tip of the silk, adheres, and begins at once to 

 grow, not upward like a seed, but down the silk throughout its 

 entire length to the ovule at its base. 



Now the pollen grain is itself, like the ovule, a sex cell, though 

 a very small one, with its nucleus and its surrounding protoplasm. 

 The latter is consumed during the progress down the silk, but 

 the nucleus descends until it reaches and unites with the nucleus 

 of the ovule. 



Fertilization. This is fertilization, after which the ovule, 

 which would otherwise wither away, is capable of developing 

 into a kernel of corn, which will be pure or mixed as to its unit 

 characters according as the two nuclei that blended for its 

 development were of the same or of different parentage. 



The unit characters of the parents are undoubtedly contained 

 in the two nuclei, and these are what decide the character of the 

 offspring. It seems inconceivable that so small a bit of matter 

 as a pollen grain or the nucleus of the ovule, each far smaller 

 than the head of a pin, can carry so many and such profound 

 potentialities ; but the character of these two nuclei alone deter- 

 mine whether the kernel shall be white, yellow, or mixed, sweet, 

 field, or pop corn. If both are from white parents, then the ker- 

 nel will be white and will transmit white characters only ; but if 

 one be from a white parent and the other from a yellow, then 

 the kernel will be mixed and will in its turn transmit both white 

 and yellow characters. Corresponding results will follow if one 

 should be field or pop corn and the other should be sweet corn. 



Moreover, this kernel, whatever its parentage, may afterward 

 "grow" and in its turn give rise to an entire new corn plant, 



kinds of protoplasm, each with its own particular function to discharge. These 

 cells lie closely packed together, like rubber bags filled with thickened water, 

 and near the center of each is its " nucleus," which is its densest portion and 

 the part which takes the initiative in cell division and growth. If it happens 

 to be a sex cell, the nucleus is the repository of the hereditary matter and the 

 seat of transmission. 



