246 
GENETICS: D. F. JONES 
the infrapolar process of the polar cartilage, the latter cartilage itself not 
fusing directly with the parachordal plate, its direct relations to the artery 
thus being obscured. 
1 Gaupp, E., Anat. Ariz., Jena, 27, 1905, (273-310). 
2 Sonies, F., Petrus Camper, Deel. 4, Jena, 1907, (395-486), Taf. 7/10. 
3 Noordenbos, W., Ibid., Deel. 3, Jena, 1905, (367-430), Taf. 6/8. 
THE EFFECT OF INBREEDING AND CROSSBREEDING UPON 
DEVELOPMENT 1 
By D. F. Jones 
Connecticut Agricultural Exferiment Station, New Haven 
Communicated by T. B, Osborne, July 12, 1918 
The experiments dealing with the effects of inbreeding and crossbreeding 
in the naturally cross-pollinated corn plant, Zea mays L., carried on at the 
Connecticut Experiment Station have been reported on previously by East 2 
and Hayes. 3 A continuation of these experiments shows that there is no 
appreciable reduction in vigor and productiveness, as indicated by the yield 
of grain and height of plant, after the eighth generation of self-fertilization 
as can be seen in table 1. The resulting inbred strains, now in the eleventh 
TABLE 1 
The Effect of Inbreeding on the Yield and Height of Maize 
FOUR INBRED STRAINS DERIVED FROM A VARIETY 
OF LEAMING DENT CORN 
NUMBER 
YEAR 
GROWN 
OF 
GENERA- 
TIONS 
1-6-1 
-3-etc. 
1-7-1-1- 
-etc. 
1-7-1-2- 
etc. 
1-9-1-2-etc. 
SELFED 
Yield 
per acre 
Height 
Yield 
per acre 
Height 
Yield 
per acre 
Height 
Yield 
per acre 
Height 
bushels 
inches 
bushels 
inches 
bushels 
inches 
bushels 
inches 
1916 
0 
74.7 
117.3 
74.7 
117.3 
74.7 
117.3 
n.i 
117.3 
1905 
0 
88.0 
88.0 
88.0 
88.0 
1906 
1 
59.1 
60.9 
60.9 
42.3 
1908 
2 
95.2 
(1907) 59.3 
(1907) 59^3 
51.7 
1909 
3 
57.9 
(1908) 46.0 
(1908) 59.7 
35.4 
1910 
4 
80.0 
63.2 
68.1 
47.7 
1911 
5 
27.7 
86.7 
25.4 
81.1 
41.3 
90.5 
26.0 
76.5 
1912 
6 
(1913) 38.9 
1913 
7 
41.8 
39.4 
(1914) 45.4 
85.0 
1914 
8 
78.8 
96.0 
47.2 
83.5 
58.5 
88.0 
(1915) 21.6 
1915 
9 
25.5 
24.8 
(1916) 30.6 
78.7 
1916 
10 
32.8 
97.7 
32.7 
84.9 
19.2 
86.9 
(1917) 31.8 
82.4 
1917 
11 
46.2 
103.7 
42.3 
78.6 
37.6 
83.8 
