former case being, in normal heterosexual relationships, a man,
in the latter a woman; they are not purely tactile phenomena, but
involve various other physical and psychic elements.
_Cunnilingus_ was a very familiar manifestation in classic times,
as shown by frequent and mostly very contemptuous references in
Aristophanes, Juvenal, and many other Greek and Roman writers;
the Greeks regarded it as a Phoenician practice, just as it is
now commonly considered French; it tends to be especially
prevalent at all periods of high civilization. _Fellatio_ has
also been equally well known, in both ancient and modern times,
especially as practiced by inverted men. It may be accepted that
both _cunnilingus_ and _fellatio_, as practiced by either sex,
are liable to occur among healthy or morbid persons, in
heterosexual or homosexual relationships. They have little
psychological significance, except to the extent that when
practiced to the exclusion of normal sexual relationships they
become perversions, and as such tend to be associated with
various degenerative conditions, although such associations are
not invariable.

The essentially normal character of _cunnilingus_ and _fellatio_,
when occurring as incidents in the process of tumescence, is
shown by the fact that they are practiced by many animals. This
is the case, for instance, among dogs. Moll points out that not
infrequently the bitch, while under the dog, but before
intromission, will change her position to lick the dog's
penis--apparently from an instinctive impulse to heighten her own
and his excitement--and then return to the normal position, while
_cunnilingus_ is of constant occurrence among animals, and on
account of its frequency among dogs was called by the Greeks