selection, it seems clear that here we are dealing with an original instinct.
The pariah dogs of Constantinople and other Eastern cities, which are practically as untamed as their fellow-scavengers the vultures, crows, and jackals, and which probably have only in the slightest degree ever come under direct human_influence, have the same habit.
Each street is the recognized dwelling-place of an irregular pack, and dogs—and in some cases even men—from other quarters are warned off or attacked if they cross the boundary.
It is said also that the wild dogs of India will drive off a tiger if he strays into the neighborhood of their chosen habitat. Even tame wolves will, without being taught, threaten a stranger if he comes near their master's house, but will take no notice of the coming and going of the regular inmates.
It would seem, therefore, that the watch-dog's peculiar virtue is directly traceable to the old instinct for guarding the lair of the pack. And in following this instinct the dog indicates that it is not his custom to act single-handed. The very fact that he growls or barks at a stranger shows that a vocal intimation to his fellows of the presence of a possible enemy is part of his plan. Every one has noticed that the barking of one dog will set off others within hearing, so that on a still night an alarm at one spot will disturb a whole suburb. Although no wolves or wild dogs are known to bark in the true canine manner, it is impossible to imagine that so distinct and almost universal a habit of the domestic varieties can have been deliberately initiated by man. Several instances are recorded of Eskimo dogs, and even dingoes and wolves, learning to bark by spontaneous imitation of domestic dogs. Foxes make a noise very like barking when they challenge one another among the hills at night, and it is not difficult to provoke an answer by imitating the sound under appropriate conditions. It seems probable, therefore, that the common ancestor of our domestic dogs and their wild relatives, which no doubt lived under somewhat different conditions from any modern feral creatures of the kind, was a barking animal.
As I have already said, the very fact that the dog barks when alarmed is an indication that he is a creature of gregarious instincts, and that he is accustomed to act in concert with others. The sound is a signal to his comrades as well as a threat to the intruder. If this be not so, what can be the meaning and intention of the different tones he adopts according to the nature of the provocation, which are capable of conveying to ears afar off an idea of the measure and nearness of the danger?
Most of our domestic animals, and all which act under our orders and give us willing obedience, are gregarious in their habits