The persistence of the mental and moral parallelism between men and wild animals is a source of constant surprise. In a state of freedom, untrammeled by anything save the fear of death by violence, the deer or the mountain sheep works out in his own way his chosen scheme for the survival of the fittest,--himself. In the wilds we see very few manifestations of the criminal instinct. A fight between wild elk bulls for the supremacy of a herd is not a manifestation of murder lust, but of obedience to the fundamental law of evolution that the largest, the strongest and the most courageous males of every herd shall do the breeding. The killing of natural prey for daily food is not murder. A starving wolf on the desolate barren grounds may even kill and devour a wounded pack-mate without becoming a criminal by that act alone. True, such a manifestation of hard-heartedness and bad taste is very reprehensible; but its cause is hunger, not sheer blackness of heart. Among wild animals, the wanton killing of a member of the killer's own species would constitute murder in the first degree, and so is all unnecessary and wanton killing outside the killer's own species. To many a wild animal there comes at tunes the murder lust which under the spur of opportunity leads to genuine crime. In some of the many cases that have come under my notice, the desire to commit murder for the sake of murder has been as sharply defined as the fangs or horns of the criminal. Of the many emotions of wild animals which are revealed more sharply in captivity than in a state of nature, the crime-producing passions, of jealousy, hatred, desire for revenge, and devilish lust for innocent blood, are most prominent. In the management of large animals in captivity, the criminal instinct is quite as great a trouble- breeder and source of anxiety as are wild-animal diseases, and the constant struggle with the elements. In many cases there is not the slightest premonitory manifestation of murderous intent on the part of a potential criminal. Indeed, with most cunning wisdom, a wild-animal murderer will often conceal his purpose until outside interference is an impossibility, and the victim is entirely helpless. These manifestations of fiendish cunning and premeditation are very exasperating to those responsible for the care of animals in captivity. In every well regulated zoological park, solitary confinement is regarded as an unhappy or intolerable condition. Animals that live in herds and groups in large enclosures always exercise more, have better appetites, and are much more contented and happy than individuals that are singly confined.