MENDEL 



A + 2Aa + a 

 B + 2Bb + b. 



Expt. 2. 



ABC, seed parents; 



A, form round; 



B, albumen yellow; 



C, seed-coat grey-brown. 

 abc, pollen parents; 



a, form wrinkled; 



b, albumen green; 



c, seed-coat white. 



This experiment was made in pre- 

 cisely the same way as the previous 

 one. Among all the experiments it de- 

 manded the most time and trouble. 

 From 24 hybrids 687 seeds were ob- 

 tained in all: these were all either 

 spotted, grey-brown or grey-green, 

 round or wrinkled.^* 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 



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 ap- 

 pears on the average 43 times. One 

 form appears 78 times and is hybrid in 

 all of the characters. The ratios 10, 19, 



1^ [Note that Mendel does not state the 

 cotyledon-colour of the first crosses in this 

 case; for as the coats were thick, it could not 

 have been seen without opening or peeling 

 the seeds.] 



13 



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 ac- 

 cording to the following expression: 



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 

 -f 4 aBbCc + 4 AaBCc + 4 AabCc 

 + 4 AaBbC + 4 AaBbc + 8 AaBbCc. 



Here also is involved a combination 

 series in which the expressions for the 

 characters A and a, B and b, C and c, 

 are united. The expressions 



A + 2Aa + a 

 B + 2Bb + b 



C +2Cc + c 



give all the classes of the series. The 

 constant combinations which occur 

 therein agree with all combinations 

 which are possible between the char- 

 acters A, B, C, a, ^, c; two thereof, 

 ABC and abc, resemble the two origi- 

 nal parental stocks. 



In addition, further experiments 

 were made with a smaller number of 

 experimental plants in which the re- 

 maining characters by twos and threes 

 were united as hybrids: all yielded ap- 

 proximately the same results. There is 

 therefore no doubt that for the whole 

 of the characters involved in the ex- 

 periments the principle applies that the 

 ojfspriiig of the hybrids i?i ivhich sev- 

 eral essentially different characters are 

 combined exhibit the terms of a series 

 of combiiiations, i?i which the develop- 

 mejital series for each pair of differen- 

 tiating characters are united. It is dem- 

 onstrated at the same time that the 



