PLant Coors IN MAIzE 15 
Three subclasses of type VI are recognized. One of these, VIa, is like 
Vic in every respect except that a slight amount of brown is sometimes 
seen in the outer husks and sheaths (Plate VI, 5). The second, VIb. is 
green except for a slight tinge of brown in the spikelets of the staminate 
_ inflorescence (Plate IV, 4). Asa rule, the development of brown pigment 
in Vla and Vib is not sufficient to differentiate with certainty the one 
from the other, or either from Vic. The three subclasses, a, b, and ec, 
are therefore usually classed together as type VI. Both Vla and VIb 
have been isolated from crosses involving VIc. The aleurone of all type 
VI plants, just as in those of type V, is colorless, except for such color as 
may be due to xenia. The pericarp of Vla and VIc is either brown or 
colorless, never brownish, while that of VIb is brown, brownish, or color- 
less, as in the case of type V. With brownish pericarp, type VIb usually 
shows unmistakable brown color in the staminate spikelets. 
RELATION OF PLANT COLORS TO ENVIRONMENT 
From the preceding descriptive notes and accompanying illustrations, 
it is clear that many of the differences separating the six major color types 
and their several subclasses are quantitative. Purple plants are -more 
strongly colored than are sun red or dilute purple plants. Dilute sun 
‘red plants have less color than sun red or purple plants. Weak purple 
plants have less color than purple ones, but more than dilute purple ones, 
and weak sun reds are intermediate between sun reds and dilute sun reds. 
Dilute sun red plants vary, from those showing considerable color to those 
which, except for green, are nearly colorless. Wholly green plants are 
classed as subgroups of both dilute. purple and dilute sun red. The 
subclasses of type VI differ so little with respect to color that they are 
ordinarily thrown together as one green type. Heterozygous brown 
plants are lighter than homozygous ones, and, since more than one factor 
pair is concerned, there is a fairly smooth gradation from the darkest to 
the lightest browns. Plants of types Vla and VIb, when they show any — 
brown, differ in the parts colored. The cclor of the staminate inflores- 
cence, and even of other parts, of purples, dilute purples, browns, and 
greens of type VIb is darker when the pericarp is cherry or brownish than 
when it is red, brown, or colorless. 
The natural intergrading of genetic types in this somewhat complex 
series is often made still more confusing by the variations accompanying 
