8 R. A. EMERSON 
been wholly subsidiary to the main purpose, namely, a genotypic analysis 
of the color types under observation. The writer’s realization of the 
superficial nature of the environmental studies reported in this account 
in no way weakens his belief in the importance of acquiring an accurate 
knowledge of the chemistry of the pigments concerned and of instituting 
fundamental investigations into the physiology of their development — 
problems that must await the interest and effort of other workers. 
The studies reported here were begun in a small way in 1909 and have 
been continued, along with other problems in the genetics of maize, to 
the present time. The work was conducted at the University of Nebraska 
and supported by funds of that institution from 1909 to 1914. During 
1911 facilities for growing and studying a considerable part of the cultures 
then in hand were generously afforded the writer by the Bussey Institu- 
tion at Harvard University. Since 1914 the work has been conducted 
at Cornell University. 
During these years, the writer has been assisted by a number of persons, 
among whom he desires to mention particularly Dr. E. W. Lindstrom and 
Dr. E. G. Anderson. Some data from the records of students associated 
with the writer are included in this account. The cultures giving these 
borrowed data are indicated in the tables by initial letters preceding the 
pedigree numbers, as follows: A = E. G. Anderson, L = E. W. Lind- 
strom, and S = Sterling H. Emerson. 
The illustrations are from water-color drawings by C. W. Redwood, 
Miss Carrie M. Preston, and Miss Bernice M. Branson. 
PREVIOUS INVESTIGATIONS 
So far as the writer is aware, little work with the plant colors of maize 
has been reported previous to this time. Webber (1906) reported the 
results of studies of the interrelations of aleurone, silk, anther, and 
glume colors, with the conclusion that color in all these parts is closely 
correlated but that there are definite breaks in the correlation. This 
conclusion, in terms of present-day usage, is apparently equivalent to 
the idea of close linkage with some crossing-over. East and Hayes (1911) 
identified certain aleurone-color genes, which are shown in the present 
account to be related to plant colors as well as. to aleurone colors, and 
reported data concerning the inheritance of silk and anther colors. The 
writer (Emerson, 1918) added another aleurone-color pair also known to 
