256 



PLANT HYBRIDIZATION BEFORE MENDEL 



tricolor also. The condition of the ancestry then, in terms of the 

 partial values of the ancestor's contribution is : 



2 parents 



4 grandparents (tricolor, calculated) 



4 grandparents (tricolor, experimental) 



each 0.2500 0.5000 

 each 0.0625 0.2500 

 each 0.0408 0.1632 



0.9132 



Case II 

 TT.TN TN.TT TT.NT NT.TT 



2 parents 



3 grandparents (tricolor, calculated) 



3 grandparents (tricolor, experimental) 



1 grandparent (non-tricolor, experimental) 



0.8342 



Case III 

 TN.TN TT.NN TN.NT NT.TN NN.TT NT.NT 



2 parents 



2 grandparents (tricolor, calculated) 



2 grandparents (tricolor, experimental) 



2 grandparents (non-tricolor, experimental) 



each 0.2500 



each 0.0625 



each 0.0408 



each 0.0243 



2000 

 1250 

 0816 

 0486 



0.7552 



Case IV 



TN.NN NN.TN NT.NN NN.NT 



2 parents each 0.2500 0.5000 

 1 grandparent (tricolor, calculated) each 0.0625 0.0625 

 1 grandparent (tricolor, experimental) each 0.0408 0.0408 



3 grandparents (non-tricolor, experimental) each 0.0243 0.0729 



0.6761 



Thus, taking the total number of tricolor cases up to the second 

 descending generation, and multiplying by the respective co- 

 efficients of each, the relation of the total sum number of tricolor 

 offspring calculated, to those observed, was as 391 .'387. The 

 data are given in detail in the following table, somewhat re- 

 arranged from Galton. In each instance, the coefficient, multiplied 

 by the number of cases, gives the theoretical or calculated num- 

 ber erf tricolor animals out of the total (the underscored number). 

 Beneath the figure of each case, is given the actual observed num- 

 ber of tricolors. 



