28o Toyama. 



b) a mixture of two heterozygous dominant whites (Ww and WY), 

 and c) a mixture of a homozygous dominant (WW) and two hetero- 

 zygous dominant whites (Ww and WY). 



a) The first F^ whites (ww and WY) mated at random will 

 produce three kinds of F2 broods, which are shown below: 



1. WW X ^\'^V = ww = Homozygous dominant white. 



2. WW -(- WY = WY -j- WW = a mixture of heterozygous and homozygous dominant 

 whites. 



3. WY X WY = WW 4- 2 WY -f YY = a mixture of 3 whites : i yellow. 



These are the Fg of monohybrid and their order of inheritance 

 in succeeding generations may easily be deduced from to the mono- 

 hybrid principle. 



b) The second F^ whites (Ww and WY) paired, inter sf will give 

 three kinds of Fo broods as shown below: 



1. Ww ■, Ww = WW -|- 2 Ww -(- WW = a mixture of various whites. 



2. Ww X WY = WW + Ww + WY + wY = 3 whites : i yellow. 



3. Wy X WY = WW + 2 WY + YY = 3 whites : I yellow. 



A result apparently similar to that of the first white mating, 

 but the zygotic constitution of each brood is entirely different from 

 the latter, as the formulae show. 



In spite of its zygotic consitution not being the same, all the 

 white F2 will remain true to parents in succeeding generations. As 

 to the mixed Fg broods, as we noted in the yellow female mating, 

 there are two kinds of 3W : i Y broods, both of which have a different 

 zygotic constitution. 



In F3, therefore, white and yellow derived from both 3 w: lY F2 

 broods will segregate according to the following formulae: 



F3 of the former 3 w : i Y brood. 



1. Whites paired mier se. 



a. WW X WW = WW = all white. 



b. WW X Ww = WW + Ww = all white. 



c. Ww X Ww = WW -|- 2 Ww -|- WW = all white. 



d. W\V X WY = WW -|- WY = all white. 



e. WY X WY = WW + 2 WY -f YY = 3 whites : i yellow. 



f. Ww X WY = \VW + Ww + WY + wY = 3 whites : I yellow. 



2. Yellows paired i>ifer se. 



As the formula shows their zygotic composition is the Fi of 

 monohybrid, their offspring will be Fg, F3 and so on in the succeeding 

 generations. 



