Table 42.—Classification of the extracted hooded individuals obtained in the second generation from a cross between hooded and wild rats.

Grade of hooded grandparents. Grade of extracted hooded grandchildren. Total. Mean. Mean, uncrossed race. Standard deviation. Standard deviation, uncrossed race.
-2 -1¾ -1½ -1¼ -1 0 ½ ¾ 1 2 3
♀ -1⅞, gen. 2½, minus series 2 4 6 5 6 13 2 1 3 4 5 3 4 2 1 1 62 + .31 -1.20 .98 .49
♀♀ -2, gen. 6, minus series 1 1 1 1 2 6 6 7 2 3 6 4 2 4 1 1 48 + .25 -1.59 .97 .44
♀♀ -2 and -2¼, gen. 10, minus series 1 3 3 1 10 3 9 8 14 4 7 8 1 4 3 5 2 4 1 91 + .24 -2.05 1.18 .24
♀♀ +3, gen. 3, plus series 1 5 3 2 3 4 2 1 21 +2.56 +2.60 .50 .53
♀♀ +3¼, gen. 5 and +3½, gen. 6, plus series 1 2 1 1 1 6 9 8 8 1 38 +2.97 +3.14 .52 .49
♀ +4¼, gen. 10, plus series 1 3 4 2 3 3 16 +3.15 +3.84 .28 .36

Table 43.—Classification of the extracted hooded individuals obtained in the second generation from a cross between hooded and Irish rats.

Grade of hooded grandparents. Grade of extracted hooded grandchildren. Total. Mean. Mean, same grade and generation, uncrossed race. Standard deviation. Standard deviation, uncrossed race.
-2 -1¾ -1½ -1¼ -1 0 +1 2 3
-1½, gen. 3½ 1 5 3 6 12 26 9 9 10 1 3 2 2 1 90 - .62 -1.31 .61 .48
-1⅞, gen. 4 6 3 4 5 9 14 8 1 1 1 1 53 - .73 -1.18 .60 .46
+2, gen. 7½ 6 6 12 11 8 3 4 4 6 1 3 1 1 66 - .94 -1.75 .84 .35
+2¼, gen. 2 3 4 5 4 16 7 16 22 25 29 24 13 33 14 8 8 6 3 239 +1.27 +1.80 .90 .75
+3, gen. 3 2 1 1 3 3 4 2 2 1 2 1 1 23 + .95 +2.50 .87 .53

Table 44.—F₃ generation produced by extracted hooded rats (F₂ generation) derived from a cross of a hooded rat of the minus series with a wild rat. (See Table 42.)

Grade of (F₂) parents. Grade of (F₃) offspring. Totals. Means. Regression.
-1 0 ¾ 1 2 3
¾ 2 1 4 3 4 1 2 1 1 19 + .04 .71
1 1 1 3 2 2 1 5 3 6 4 3 1 1 34 +2.06 .44

Table 45.—F₄ generation from minus series crossed with wild.

Grade of (F₃) parents. Grade of (F₄) offspring. Totals. Means. Regression.
0 ¾ 1 2 3
2 1 1 3 6 6 9 16 25 14 10 2 1 96 1.78 .47
2⅜ 2 1 1 1 6 3 8 3 9 4 4 1 1 44 1.67 .70
2⅞ 1 2 1 1 1 1 1 8 .91 1.96
3 1 1 3 3 5 9 5 7 3 1 1 39 2.02 .98
3⅛ 1 1 3 1 2 5 4 1 18 2.82 .30
Totals or means, 2.52 3 3 1 5 5 16 10 22 26 47 20 23 14 7 1 2 205 1.86 .66