FOREWORD 7 
kittens when they were seven weeks old. Some of the 
domestic animals devour their young ; the sow often does 
it, and occasionally the bitch. 
Sucking, gnawing and eating parts of itself or of a 
cage-mate is not uncommon in a variety of animals. Bears 
lick their paws until they are sore ; a monkey may gradu- 
ally gnaw away its tail from the tip to the body ; an ocelot 
{Felts chibigonason) bit open his scrotum and devoured 
his testicle; a Tasmanian devil (Sarcophilus ursinus) bit 
off one of his front feet at the wrist; a monkey may 
gradually gnaw away its fingers ; and numerous other 
self-inflicted mutilations occur. Often there is a local 
irritating cause, as skin disease, lice, or freezing. But 
in many cases no local cause can be found, as no local 
cause can be found for thumb-sucking or nail-biting in 
the human. 
The surgery done by monkeys on their frozen fingers 
and toes is interesting. After the flesh has sloughed the 
monkey bites off the protruding phalanges, apparently 
without pain, so that satisfactory well-covered stumps 
are made. 
Animals often mutilate their cage-mates in an 
amicable way as distinguished from fighting. A bear may 
lick its mate's ears until the hair and skin are gone. A 
monkey may eat its mate's tail or patches of its skin, the 
victim lying placidly while the process goes on. Many 
animals are addicted to perverted acts on their own or 
their mate's sexual organs. 
It is probable that the phenomena just mentioned are 
due to confinement, idleness and ennui, and that they do 
not often happen in nature where an animal is kept busy 
seeking his food, fighting and avoiding his enemies, 
attending to his mate or mates, and meeting the various 
vicissitudes of his environment. 
It should be remembered, however, that the members 
of a wild species vary in intelligence and temperament, as 
humans do. There are morons and perverts among 
