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, ab, resemble the parental forms, the two others 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 b, are combined. We arrive at the full number of the classes of the series by the combination of the expressions:
A + 2 Aa + a
B + 2 Bb + b.
Second Expt.
| ABC, | seed parents; | abc, | pollen parents; |
| A, | form round; | a, | form angular; |
| 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 angular[37]. 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 | " | aBCc. | 38 | " | AaBCc. |
11 | " | Abc. | 20 | " | abCc. | 40 | " | AabCc. |
8 | " | aBC. | 15 | " | ABbC. | 49 | " | AaBbC. |
10 | " | aBc. | 18 | " | ABbc. | 48 | " | AaBbc. |
10 | " | abC. | 19 | " | aBbC. | |||
7 | " | abc. | 24 | " | aBbc. | |||
14 | " | AaBC. | 78 | " | AaBbCc. | |||
18 | " | AaBc. | ||||||
20 | " | AabC. | ||||||
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.