Table 47.—Distribution of frequency of the different grades of "openness" of nostril when one parent is heterozygous and the other recessive, i. e., with closed nostril (DR × R).

Serial
No.
Pen
No.
Mother.Father.Total
gr.
Grade of openness in offspring.
No.Gen.Races.Gr.No.Gen.Race.Gr. 1 2 3 4 5 6 7 8 9 10
13768298F2Med. × Polish21689P.Med.13119313...1.........
14768509F1Do.11689P.Do.12125611...............
Totals (53)231492401.........
Percentages43.426.417.03.87.6...1.9.........

The study of the tables 45 to 54 establishes the following conclusions:

First, high nostril is dominant. This means that there is a factor that inhibits the development of the narial flap. In the absence of such a factor the flap goes on developing normally. This hypothesis is opposed to the conclusion that I reached in my report of 1906 (pp. 68, 69). I there said:

A close agreement exists between the percentage obtained in each generation and the expectation of the Mendelian theory, assuming that narrow nostril is dominant. The statistics do not, however, tell the whole story. In 36 per cent of the cases in the F1 generation the nostril was wider than in the "narrow" ancestor. Even in the F2 generation nearly half of the "narrow and intermediate" were of the intermediate sort. This intermediate form is evidence that dominance is imperfect and segregation is incomplete.

Table 48.—Distribution of frequency of grades of "openness" in offspring when both parents are heterozygous (DR × DR).

Serial
No.
Pen
No.
Mother.Father.Total
gr.
Grade of openness in offspring.
No.Gen.Races.Gr.No.Gen.Races.Gr. 1 2 3 4 5 6 7 8 9 10
158025314F1Polish × Min.36652F1Polish × Min.47155......1......31
168055307F1Do.54799F1 Do.277713371...221
178525104F1Hou. × Dk. Br.35969F1Hou. × Dk. Br.3641142111.........
188054800F1Polish × Min.34799F1Polish × Min.2510139128...12...
198055308F1Do.34799F1Do.2537321...............
21759797F1Houd. × Min.3570F1Houd. × Min.252422...............2
22759797F1Do.3352F1Do.14...22...............11
238054447F1Polish × Min.24799F1Polish × Min.24654...2...113...
248054765F1Do.24799F1Do.2451242112...2...
258054797F1Do.24799F1Do.24426............1......
268055163F1Do.24799F1Do.2471713412221...
278055304F1Do.24799F1Do.24598...1...............
288527070F1Hou. × Dk. Br.15969F1Hou. × Dk. Br.3441142111.........
29759529F1Houd. × Min. 2570F1Houd. × Min.2423.....................1
30759529F1Do.2352F1Do.2413........................
31728174F1Hou. × Wh.L.1258F1Hou. × Wh.L.232721111.........
328054798F1Polish × Min.14799F1Polish × Min.237103212...42...
338055323F1Do.14799F1Do.231772......1...21...
Totals (435)92147882122191013176
Percentages21.233.820.24.85.04.42.33.03.91.4

Table 49.—Distribution of frequency of grades of "openness" in offspring when both parents are heterozygous (DR × DR, F2 and later generations).

Serial
No.
Pen
No.
Mother.Father.Total
gr.
Grade of openness in offspring.
No.Gen.Races.Gr.No.Gen.Races.Gr. 1 2 3 4 5 6 7 8 9 10
347633799F2Hou. × Wh. L.62247F2Hou. × Wh. L.28...2222...1.........
3576584F1Do.31794F2Do.581681411263
36765984F2Do.31794F2Do.58831221025...
378024013F2Polish × Min.46652F1Polish × Min.4861296.........111
388023954F3Do.36652F1Do.47412321...2691
398024038F2Do.36652F1Do.4738432...1411
408024164F2Do.36652F1Do.47686211...222
4181284F1Hou. × Wh. L.34118F3Hou. × Wh. L.47...152211112
42812913F2Do.34118F3Do.4710661.........325
438124728F3Do.34118F3Do.478551522292
448125120F3Do.34118F3Do.47122...1.........12
458125540F3Polish × Min.34118F3Do.4725611...............
467632250F3Hou. × Wh. L.52247F2Do.274102............102
478124726F2Do.24118F3Polish × Min.46463...21...213
488124735F2Do.24118F2Do.46211............21...
497651790F3Do.11794F2Hou. × Wh. L.569149130203...
508024012F3Polish × Min.16652F1Polish × Min.455131132...131...
518252198F3Do.3 3852F3Do.25......13...............1
527282271F2Hou. × Wh. L.3258F1Hou. × Wh. L.254317213112
537632700F2Do.32247F2Do.251233...1......2...
54825350F1Polish × Min.23852F3Polish × Min.2441364.........313
558254708F3Do.23852F3Do.2441373...11123
568255019F2Do.23852F3Do.2411...............122
578255035F3Do.23852F3Do.244...311......111
588255672F3Do.23852F3Do.24132...2......121
597282248F2Hou. × Wh. L.2258F1Hou. × Wh. L.243672......1013
61763377F1Do.12247F2Do.23209143602021
Totals (663)1156411275339108395741
Percentages17.424.719.28.05.91.52.75.98.66.2
69.330.7

These earlier data were not even roughly quantitative, and it is the quantitative data that first give the key to the true relations. However, sufficient evidence for the change in the conclusion is certainly due. The evidence is found in a careful study of table 55, keeping constantly in mind this fundamental principle that the recessive condition alone in the parents can never give rise to the dominant; for the recessive condition implies entire absence of the dominant factor. But the pure dominant condition will vary in the direction of the recessive condition; such a result implies only a partial failure of the factor to develop completely; and we should not be surprised if occasionally the failure were complete. This implies no "reversal of dominance," but rather an arrested development of the factor.