In my work on “Sleep” I report a series of interesting experiments carried out by me on guinea pigs, rabbits, cats, dogs, children, and adults.[4] I discovered one of the most important states of animal life, a state which I termed hypnoidal.

The study shows that in almost every animal, from the lowest to the highest, from frog to man, a somewhat sudden change of the usual environment deprives that animal of its activities and its functions. If the change is not too intense and prolonged, the animal merges into the hypnoidal state in which the lost functions are restored. During this hypnoidal state the functions are weakened, the animal may be regarded in a state of invalidism, its reactions being enfeebled, practically speaking, paretic.

Perhaps it is advisable to approach the phenomena from their more striking aspect. In seizing a triton, salamander, or frog, and stretching it on the table, one will observe with surprise that the[67] animal remains in the same position given it. The most uncomfortable and bizarre position may be given to the limbs, and still the animal will not move. Testing the extremities one finds them rigid and resisting. Something similar we find in the hypnotic condition, when under the suggestion that the extremities are rigid, and they cannot be moved by the subject. The same can be done with a lobster and other animals of the same type.

Everyone has heard of the experimentum mirabile made by Kirchner in the seventeenth century. A rooster or hen is seized, the legs are tied with a string and the bird is put on the ground. A piece of chalk is passed over the beak,—the chalk tracing a line from beak to some distant point on the ground. When the bird is released, it remains in the same position. Some explain that the animal is kept prisoner, because it “imagines” that it is bound by the line of chalk. The chalk, however, is unnecessary. The animal may be seized, shouted in its ear, or kept down forcibly, and the same result will happen. This state has been termed by Preyer “cataplexy.” The phenomenon can also be produced in insects, in mollusca.

Many investigators have been interested in this phenomenon. I have devoted a good deal of work to this condition which is also found in mammals in which it is induced by the fear instinct. In mammals, however, the state of cataplexy is not necessarily[68] accompanied by rigidity, although it may be present, but there is a complete loss of voluntary activity. Horses tremble violently and become paralyzed at the sight of a beast of prey, such as a tiger or a lion. At the sight of a serpent, monkeys are known to be in such an intense state of fear that they are unable to move, and thus fall easy victims to the reptile.

Under similar conditions birds are so paralyzed by fear that they are unable to fly away from the source of danger, and fall a prey to the threatening serpent. The birds resemble very much the hypnotized subject in a state of catalepsy. Although the gibbons are the most agile of all the simians, they are easily taken by surprise, and captured without any resistance,—they are paralyzed by fear. Seals when pursued on land become so frightened that they are unable to offer any opposition to their pursuers, and let themselves easily be captured and killed.

In large cities one can often witness nervous people affected suddenly by the presence of danger; they remain immobile, in the middle of the street, becoming exposed to fatal accidents. The fear instinct paralyzes their activities, they are petrified with terror.

I was told by people who have experienced the effects of earthquakes, that during the time of the[69] earthquakes they were unable to move, and the same condition was observed in animals, especially in young dogs. It is hard to move cattle and horses from a burning stable, on account of the fear of fire which obsesses the animals, so that they become paralyzed, suffocated and burnt to death. So vital is the fear instinct that the least deviation from the normal state is apt to play havoc with the safety of the individual.

The fear instinct is the most primitive, the most fundamental, and the most powerful of all instincts. When the fear instinct is let loose, the animal succumbs. We should not wonder, therefore, that with the aberration of the fear instinct, the life guardian of the individual, all orientation is............