monkey, but often also to their old monkey friends; and after this
mutual display they begin to play together. The young mandrill ceased
spontaneously after a time to act in this manner towards his master,
von Fischer, but continued to do so towards persons who were strangers
and to new monkeys. A young Cynopithecus niger never acted, excepting
on one occasion, in this way towards his master, but frequently towards
strangers, and continues to do so up to the present time. From these
facts Von Fischer concludes that the monkeys which behaved in this
manner before a looking-glass (viz., the mandrill, drill, Cynopithecus
niger, Macacus rhesus and nemestrinus) acted as if their reflection
were a new acquaintance. The mandrill and drill, which have their
hinder ends especially ornamented, display it even whilst quite young,
more frequently and more ostentatiously than do the other kinds. Next
in order comes Cynocephalus hamadryas, whilst the other species act in
this manner seldomer. The individuals, however, of the same species
vary in this respect, and some which were very shy never displayed
their hinder ends. It deserves especial attention that Von Fischer has
never seen any species purposely exhibit the hinder part of its body,
if not at all coloured. This remark applies to many individuals of
Macacus cynomolgus and Cercocebus radiatus (which is closely allied to
M. rhesus), to three species of Cercopithecus and several American
monkeys. The habit of turning the hinder ends as a greeting to an old
friend or new acquaintance, which seems to us so odd, is not really
more so than the habits of many savages, for instance that of rubbing
their bellies with their hands, or rubbing noses together. The habit
with the mandrill and drill seems to be instinctive or inherited, as it
was followed by very young animals; but it is modified or guided, like
so many other instincts, by observation, for Von Fischer says that they
take pains to make their display fully; and if made before two
observers, they turn to him who seems to pay the most attention.
With respect to the origin of the habit, Von Fischer remarks that his
monkeys like to have their naked hinder ends patted or stroked, and
that they then grunt with pleasure. They often also turn this part of
their bodies to other monkeys to have bits of dirt picked off, and so
no doubt it would be with respect to thorns. But the habit with adult
animals is connected to a certain extent with sexual feelings, for Von
Fischer watched through a glass door a female Cynopithecus niger, and
she during several days, umdrehte und dem Mannchen mit gurgelnden
Tonen die stark gerothete Sitzflache zeigte, was ich fruher nie an
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