174
V. G. DETHIER
tion received through the antennae, because antennaless females reject
the overtures of the male, probably through not receiving necessary
stimuli. If the female repels the male by extruding, the posturing male
turns away abruptly in a manner which suggests reception of a repellent
olfactory stimulus. It is believed that the female receives from the
posturing male a variety of stimuli some of which are tactile, some visual,
and some chemical. It is certain in the cases of Orosophila
mehnogaster,
D. persimilis, and D. pseudoobscura
that the female is capable of discriminating between conspeciflc and foreign males. Streisinger (1948)
examined this question by placing various males with various females
which had been etherized. Before placing the female in with the male
Streisinger squeezed the ovipositor of the female so that she was exhibiting a maximum acceptance response. Under these conditions males
of D. pseudoobscura,
which inseminated their own females in preference
to those of D. persimilis at a ratio of nine to one, inseminated etherized
females of both species equally. The reaction of D. mehnogaster
toward
its own females and those of D. persimilis was similar. Differential
insemination disappeared when the females were etherized. D. mehnogaster males tap and lick in the course of mating, while the other two
species do not. Yet it would seem either that males of D.
mehnogaster
do not differentiate between their own and other females or that they
are less restricted in their mating behavior. Certainly in all of the above
crosses it is the female which differentiates. It is probable that a female
in the acceptance pose emanates an odor which stimulates the male
(Sturtevant, 1915). Etherized females which had been squeezed would,
therefore, be giving oft this material. Other evidence relative to the
importance of odor is negative, however. Female juices expressed on
filter paper failed to excite males, and females in a porous bag were likewise ineffective (Sturtevant, 1915).
Mayr (1950) pursued this problem with the same species. Normal
wild-type females of D. mehnogaster
are averse to mating with yellow
males, whereas the normal males do not discriminate against the color
of the females. If the antennae of females are removed, the insects are
no longer capable of discriminating. Removal of the proboscis, an operation of comparable or greater severity, is without significant effect as far
as discrimination is concerned. In the case of D. persimilis and D.
pseudoobscura
removal of the antennae (of D. pseudoobscura)
again
abolishes the ability to discriminate. Spieth (1952) conducted experiments with D. persimilis and D. pseudoobscura
to measure the importance of summing of stimuli from different sensory areas in evoking
sexual responses. His experiments on the summing between light and
the sensations mediated through the antennae illustrated the importance
V. G. DETHIER
tion received through the antennae, because antennaless females reject
the overtures of the male, probably through not receiving necessary
stimuli. If the female repels the male by extruding, the posturing male
turns away abruptly in a manner which suggests reception of a repellent
olfactory stimulus. It is believed that the female receives from the
posturing male a variety of stimuli some of which are tactile, some visual,
and some chemical. It is certain in the cases of Orosophila
mehnogaster,
D. persimilis, and D. pseudoobscura
that the female is capable of discriminating between conspeciflc and foreign males. Streisinger (1948)
examined this question by placing various males with various females
which had been etherized. Before placing the female in with the male
Streisinger squeezed the ovipositor of the female so that she was exhibiting a maximum acceptance response. Under these conditions males
of D. pseudoobscura,
which inseminated their own females in preference
to those of D. persimilis at a ratio of nine to one, inseminated etherized
females of both species equally. The reaction of D. mehnogaster
toward
its own females and those of D. persimilis was similar. Differential
insemination disappeared when the females were etherized. D. mehnogaster males tap and lick in the course of mating, while the other two
species do not. Yet it would seem either that males of D.
mehnogaster
do not differentiate between their own and other females or that they
are less restricted in their mating behavior. Certainly in all of the above
crosses it is the female which differentiates. It is probable that a female
in the acceptance pose emanates an odor which stimulates the male
(Sturtevant, 1915). Etherized females which had been squeezed would,
therefore, be giving oft this material. Other evidence relative to the
importance of odor is negative, however. Female juices expressed on
filter paper failed to excite males, and females in a porous bag were likewise ineffective (Sturtevant, 1915).
Mayr (1950) pursued this problem with the same species. Normal
wild-type females of D. mehnogaster
are averse to mating with yellow
males, whereas the normal males do not discriminate against the color
of the females. If the antennae of females are removed, the insects are
no longer capable of discriminating. Removal of the proboscis, an operation of comparable or greater severity, is without significant effect as far
as discrimination is concerned. In the case of D. persimilis and D.
pseudoobscura
removal of the antennae (of D. pseudoobscura)
again
abolishes the ability to discriminate. Spieth (1952) conducted experiments with D. persimilis and D. pseudoobscura
to measure the importance of summing of stimuli from different sensory areas in evoking
sexual responses. His experiments on the summing between light and
the sensations mediated through the antennae illustrated the importance