s of the
wing are _fused_ into one vein from the base of the wing to the level of
the first cross-vein and in addition converge and meet near their outer
ends. The shape of the eye is represented in the figure as different from
the normal, due to another factor called "bar". This is a dominant
character, the hybrid condition being also narrow, but not so narrow as the
pure type. Vermilion eye color might also be here represented--due to a
factor that has appeared independently on several occasions.

In the fifth figure (e) the wings are shorter and more pointed than in the
wild fly. This character is called miniature. The light color of the
drawing may be taken to represent yellow body color, and the light color of
the eye white eye color.

In the last figure (f) the wings are represented as pads, essentially in
the same condition that they are in when the fly emerges from the pupa
case. Not all the flies of this stock have the wings in this condition;
some have fully expanded wings that appear normal in all respects.
Nevertheless, about the same percentage of offspring show the pads
irrespective of whether the parents had pads or expanded wings.

The flies of this stock show, however, another character, which is a
product of the same factor, and which is constant, i.e., repeated in all
individuals. The two bristles on the sides of the thorax are constantly
absent in this race. The lighter color of the eye in the figure may be
taken to indicate buff--a faint yellowish color. The factor for this eye
color is another allelomorph of white.

There are many other interesting characters that belong to the first group,
such as abnormal abdomen, short legs, duplication of the legs, etc. In
fact, any part of the body may be affected by a sex-linked factor.

_Group II_

In the first figure (a) of figure 54 that contains members of Group II the
wings are almost entirely absent or "vestigial". This condition arose at a
single step and breeds true, although it appears to be influenced to some
extent by temperature, also by modifiers that sometimes appear in the
stock. Purple eye color belongs in Group II; it resembles the color of the
eye of the wild fly but is darker and more translucent.

[Illustration: FIG. 54. Group II. (See text.)]

In the second figure (b) the wing is again long and narrow and sometimes
bent back on itself, as shown here. In several respects the wing resembles
strap (d) but seems to be due to another f