330 



16 " Aabc 



The whole expression contains 27 terms. 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 undoubtedly represents the true value. 



The development of the hybrids when the original parents differ 

 in three characters results therefore according to the following 

 expression : 



ABC + ABc + AbC + Abe + 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 + 4 AaBCc 

 -f 4 AabCc + 4 AaBbC + 4 AaBbc + 8 AaBbCc. 



Here also is involved a combination series in which the expres- 

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

 The expressions 



A + 2Aa + a 



B + 2Bb + b 



C + 2C'c + 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, 6, c; two thereof, ABC and abc, 

 resemble the two original parental stocks. 



In addition, further experiments were made with a smaller num- 

 ber of experimental plants in which the remaining characters by 



