A very different result is obtained from the cross between the mutant and narrow races. Although F₁ from that cross was quite variable (see Table 52), F₂ is still more variable (see Table 55). The lower group F₁ individuals, which resembled F₁ between the plus and minus races, produced 61 young (first division of Table 55), which resemble F₂ between the plus and minus races. They range in grade from -2 to +3¼, mean +0.58, standard deviation 1.17. In the two series of crosses between the plus and minus races (Table 50) the means were +0.24 and +0.72, respectively, and the standard deviations 1.01 and 0.87. This indicates, as did the cross with the plus series, that the “lower group” gametes produced by the original mutant male did not differ materially from gametes produced by the ordinary plus race from which the mutant sprang. The second division of Table 55 shows the character of the F₂ young produced by the upper group of F₁ offspring recorded in Table 52. It consists of two groups, a lower and an upper. The lower represents the extracted minus race, the upper represents the extracted dominants or mutants, whether homozygous or heterozygous. The former group has an average of +0.75 and a standard deviation of 1.03, which values are close to the corresponding constants of Series 2, Table 50, the latest of the plus-minus crosses, in which the mean was +0.72 and the standard deviation 0.87. The upper group offspring of Table 55, second division, the homozygous and heterozygous mutants, number 68; they have a mean grade of 4.77 as compared with 4.43 in F₁, which consisted exclusively of heterozygotes. This shows the extracted homozygotes to be of higher grade than the heterozygotes. The highest grade mutant among the 31 F₁ young, all of which were heterozygotes, was of grade 5, but among the 68 F₂ young are 16 of higher grade than 5. We expect one-third of these 68 individuals to be homozygotes. Now all of the F₂ mutants from the cross of mutant with plus race (Table 54) were of grade 5 or higher, only 2 in 79 being as low as 5, and 13 of the 79 being of grade 5¾, a grade not attained at all in F₂ from the mutant-minus cross (Table 55). This result shows us that the cross with the minus race does affect permanently the mutant character, lowering its grade even in homozygous mutants extracted from the cross. It also increases the variability of the mutants, for the standard deviation of the mutant group in Table 55 is 0.44, whereas in Table 54 (mutant-plus F₂), in a like number of individuals, it was 0.15, or only about one-third as great.