INHERITANCE IN MAIZE 179 
a yellow strain the grains are yellow. On the other 
hand, the grains upon a plant belonging to a yellow 
strain retain their yellow colour even if the flowers 
which produce them have been pollinated from a white 
variety. 
These facts are expressed in technical language by 
saying that yellowness is dominant over whiteness, and 
the latter is said to be recessive. 
Let us now suppose that we have sown a number 
of the yellow grains derived from the cross yellow x 
white* or white x yellow, and that we have exposed 
the female flowers of the resulting plants at the proper 
stage of their existence to the influence of pollen 
derived from a pure white strain, taking care that 
none of their own hybrid pollen falls upon them at 
the same time. The result of this experiment takes 
us at once to the very heart of the Mendelian theory. 
Half the total number of grains obtained in this way 
—from the cross (white x yellow) x white—are white, 
and half are yellow. 
Thus in an experiment carried out in the manner 
described there were obtained upon ninety-five plants : 
Yellow grains 26,792, or 50°03 per cent. 
White grains 26,751, 5, 49°97 iy 
But we must go further than this. On sowing the 
white grains obtained in this second generation (F,), 
and allowing the plants obtained from them mutually 
to pollinate one another, cobs were obtained bearing 
exclusively white grains without any trace of yellow- 
ness. 
* x is to be read ‘ fertilized with pollen from.’ 
I2—2 
