340 
Journal of Agricultural Research voi. xxvn. No. 6 
Very pronounced heterosis is shown by hybrids between these types, 
yet the degree of selective fertilization in this case was much smaller 
than in some of the maize combinations tested by Jones, in which, when 
double-pollinated, there was a near approach to cross-sterility. It re¬ 
mains to be ascertained whether Gossypium is analogous to Zea in 
showing a smaller degree of selective fertilization between more nearly 
related forms. 11 
LITERATURE CITED 
(1) Balls, W. Lawrence. 
1912. THE cotton plant in Egypt, xvi, 202 p., 71 fig., i pi. London. Bib¬ 
liography, p. 181-190. 
(2) Heribert-Nilsson, Nils. 
1920. zuwachsgeschwindigkeit der pollenschlauche und gestorte 
mendelzahlen bei oenothera lamarckian a. In Hereditas, V. I, 
p. 41-67, i fig. English summary, p. 64-66. Zitierte Literatur, p. 
66-67. 
(3) Jones, D. F. 
1920. selective fertilization in pollen mixtures. In Proc. Nat. Acad. 
Sci., v. 6, p. 66-70. 
1920. SELECTIVE FERTILIZATION IN POLLEN MIXTURES. In Biol. Bui., v. 38, 
p. 251-289. Literature cited, p. 288-289. 
(s)- 
1922. SELECTIVE FERTILIZATION AS AN INDICATOR OF GERMINAL DIFFERENCES. 
In Science, n. s., v. 55, p. 348-349. 
( 6 ) - 
1922. SELECTIVE FERTILIZATION AND THE RATE OF POLLEN-TUBE GROWTH. 
In Biol. Bui., v. 43, p. 167-174, 2 fig. 
(7) Kearney, Thomas H. 
1923. SELF-FERTILIZATION AND CROSS-FERTILIZATION IN PIMA COTTON. U. S. 
Dept. Agr. Bui. 1134, 68 p., 4 fig., 7 pi. Literature cited, p. 66-68. 
( 8 ) - 
192,3. SEGREGATION AND CORRELATION OF CHARACTERS IN AN UPLAND- 
EGYPTIAN COTTON HYBRID. U. S. Dept. Agr. Bui. 1164, 58 p., 41 fig., 
21 pi. Literature cited, p. 56-57. 
(9) McClelland, T. B. 
1919. INFLUENCE OF FOREIGN POLLEN ON THE DEVELOPMENT OF VANILLA 
fruits. In Jour. Agr. Research, v. 16, p. 245-252, pi. 31-35. 
(10) Tokugawa, Y. 
1914. zur physiologie des pollens. In Jour. Col. Sci. Imp. Univ. Tokyo, 
v. 35, art. 8, 53 p., 2 fig. Literaturverzeichnis, p. 52-53. 
11 The results of experiments made by Balls (1, p. 122-125) indicate that the analogy exists, for he found 
that when either Egyptian or Upland cotton was pollinated with a mixture of pollen of the same type 
and pollen from Egyptian X Upland Fi plants, the percentage of hybrids resulting was much higher than 
when a mixture of Egyptian and Upland pollens was applied to the stigmas. This is in conformity with 
fones’ findings in Zea, since the first generation hybrid is, of course, more nearly related to either parent 
than is the other parent. 
