APPENDIX . 329 



characters, and behaves exactly as do the hybrids from which it is 

 derived. 



If the numbers in which the forms belonging to these classes 

 appear be compared, the ratios of 1, 2, 4 are unmistakably evident. 

 The numbers 32, 65, 138 present very fair approximations to the 

 ratio numbers of 33, 66, 132. 



The developmental series consists, therefore, of nine classes, of 

 which four appear therein always once and are constant in both 

 characters; the forms AB, ah, resemble the parental forms, the 

 two other present combinations between the conjoined characters 

 A, a, B, b, which combinations are likewise possibly constant. 

 Four classes appear always twice, and are constant in one character 

 and hybrid in the other. One class appears four times, and is 

 hybrid in both characters. Consequently the offspring of the 

 hybrids, if two kinds of differentiating characters are combined 

 therein, are represented by the expression 



AB-{-Ab-\- aB + ab-\- 2ABb + 2aBb + 2AaB + 2Aab + 4AaBb. 



This expression is indisputably a combination series in which the 

 two expressions for the characters A and a, B and 6 are combined. 

 We arrive at the full number of the classes of the series by the 

 combination of the expressions : 



A + 2Aa + a 

 B -\^%Bb + b. 

 Expt. 2. 



ABC, seed parents; abc, pollen parents; 



A, form round; a, form wrinkled; 



B, albumen yellow; b, albumen green; 



C, seed-coat grey-brown. c, seed-coat white. 



This experiment was made in precisely the same way as the 

 previous one. Among all the experiments it demanded the most 

 time and trouble. From 24 hybrids 687 seeds were obtained 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 : 



^ [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.] 



