ence of the other
sex.[2] This was known to the ancients; the Egyptians regarded two male
partridges as the symbol of homosexuality, and Aristotle noted that two
female pigeons would cover each other if no male was at hand. Buffon
observed many examples, especially among birds. He found that, if male or
female birds of various species--such as partridges, fowls, and
doves--were shut up together, they would soon begin to have sexual
relations among themselves, the males sooner and more frequently than the
females. More recently Sainte-Claire Deville observed that dogs, rams, and
bulls, when isolated, first became restless and dangerous, and then
acquired a permanent state of sexual excitement, not obeying the laws of
heat, and leading them to attempts to couple together; the presence of the
opposite sex at once restored them to normal conditions.[3] Bombarda of
Lisbon states that in Portugal it is well known that in every herd of
bulls there is nearly always one bull who is ready to lend himself to the
perverted whims of his companions.[4] It may easily be observed how a cow
in heat exerts an exciting influence on other cows, impelling them to
attempt to play the bull's part. Lacassagne has also noted among young
fowls and puppies, etc., that, before ever having had relations with the
opposite sex, and while in complete liberty, they make hesitating attempts
at intercourse with their own sex.[5] This, indeed, together with similar
perversions, may often be observed, especially in puppies, who afterward
become perfectly normal. Among white rats, which are very sexual animals,
Steinach found that, when deprived of females, the males practise
homosexuality, though only with males with whom they have long associated;
the weaker rats play the passive part. But when a female is introduced
they immediately turn to her; although they are occasionally altogether
indifferent to sex, they never actually prefer their own sex.[6]

With regard to the playing of the female part by the weaker rats it is
interesting to observe that Fere found among insects that the passive part
in homosexual relations is favored by fatigue; among cockchafers it was
the male just separated from the female who would take the passive part
(on the rare occasions when homosexual relations occurred) with a fresh
male.[7]

Homosexuality appears to be specially common among birds. It was among
birds that it attracted the attention of the ancients, and numerous