EXPEKIMENTS IN PLANT HYBRIDISATION. 



15 



brown or grey-green, round or angular. From these in the following 

 year 639 plants fruited, and, as further investigation showed, there were 

 among them : 



8 plants ABC. 



22 plants ABCc. 



45 plants ABbCc. 



14 



ABc. 



17 



)) 



AbCc. 



36 



?> 



aBbCc. 



9 , 



, AbC. 



25 



J) 



aBCc. 



38 



J) 



AaBCc. 



11 , 



, Abe. 



20 



j> 



abCc. 



40 



)> 



AabCc. 



8 , 



, aBC. 



15 



5> 



ABbC. 



49 





AabbC. 



10 , 



, aBc. 



18 



?> 



ABbc. 



48 



5> 



AaBbc. 



10 , 



, abC. 



19 



>) 



aBbC. 









7 , 



, abc. 



24 





aBbc. 













14 



J> 



AaBC. 



78 



>> 



AaBbCc 







18 



5) 



AaBc. 













20 



?5 



AabC. 













16 



35 



Aabc. 









The developmental series embraced 27 classes. Of these 8 are 

 constant in all characters, and each appears on the average 10 times ; 

 12 are constant in two characters, and hybrid in the third, each 

 appears on the average 19 times ; 6 are constant in one character 

 and hybrid in the other two ; each appears on the average 43 times. 

 One form appears 78 times and is hybrid in all of the characters. The 

 ratios 10, 19, 43, 78 agree so closely with the ratios 10, 20, 40, 80, or 

 1, 2, 4, 8, that this last undoubtedy represents the true .value. 



The development of the hybrids when the original parents differ in 

 three characters results therefore according to the following formula : 



ABC + ABc + AbC + Abc + aBC + aBc + abC + abc + 2 ABCc + 

 2 AbCc +2 aBCc +2 abCc +2 ABbC + 2 ABbc +2 aBbC + 2 aBbc + 

 2 AaBC + 2 AaBc + 2 AabC + 2 Aabc + 4 ABbCc + 4 aBbCc -h 

 4 AaBCc + 4 AabCc + 4 AaBbC + 4 AaBbc + 8 AaBbCc. 



Here also is involved a combination series in which the developmental 

 series for the characters A and a, B and b, C and c, are united. The 

 formulae 



A + 2 Aa + a 

 B + 2Bb + b 

 C + 2 Cc + c 



give all the classes of the series. The constant combinations which 

 occur therein agree with all combinations which are possible between the 

 characters A, B, C, a, b, c ; two thereof, ABC and abc, resemble the two 

 original parental stocks. 



In addition, further experiments were made with a smaller number 

 of trial plants in which the remaining characters by twos and threes were 

 united as hybrids : all yielded approximately the same results. There is 

 therefore no doubt that for the whole of the characters involved in the 

 trials the principle applies that the offspring of the hybrids i)i wlticJi 

 several essentially different characters are combined represent the com- 

 ponents of a series of combinations, in luhich the developmental series for 

 each two different characters are associated. It is demonstrated at the 



