Happy as long as they can help in the fighting, restless and uneasy whenever sent back to the hospitals for treatment or rest, these dogs have shown the worth of all the training they have received, as well as a great amount of natural intelligence. While Zip, Napoleon, Spot, Stop, Mignon, and Bouée have been doing their bit on the firing line, still others have been taking their training in readiness to go to the front. And very hard training it is. Sheep dogs, fox terriers, bulldogs, collies, St. Bernards, Newfoundlands, Alaskan wolf dogs, mongrels,--all must be carefully trained by expert dog trainers. First they must learn to distinguish between the uniform of their country and that of the enemy. They must not bark, because then the enemy will be sure to shoot. In carrying letters from post to post, they must learn to recognize the posts by name. [Illustration: A FRENCH OFFICER AND HIS DOG BOTH WEARING ANTI-GAS MASKS WHILE CROSSING A DANGEROUS ZONE IN FRANCE _Copyright by Underwood & Underwood, N.Y._] About three months of training are necessary to teach the dogs to travel as far as three kilometres in this work. Two of the dogs are put into the care of two trainers, and taught to recognize both as their masters, and to carry dispatches from one to the other. The dogs must be trained to obey implicitly. If the master stops abruptly in his walk, the dog must do the same; if the trainer runs, the dog must keep in perfect step, ready at a given signal to lie down, or follow a scent, or find a wounded soldier. For many hours he must be trained in jumping, because of the great heights over which he must spring, carrying heavy weights in his mouth or upon his back or around his neck. He must learn to make no sound except when ordered to do so, to find objects which have been most skillfully hidden, to distinguish between a dead man and one wounded and breathing, to deliver the token of a wounded man only to the doctor or Red Cross nurse, to allow nothing to hinder him from carrying out any task, to refuse food and water from strangers, and to aid soldiers on the watch. These watch dogs must learn to give a signal when they scent poison gas or hear the enemy creeping up. And they must guard prisoners very carefully. Some dogs cannot learn all of these duties, and so specialists examine every dog that is enlisted. There are tests for health, intelligence, speed, quick tempers, and even tempers. When a dog has been in training for several weeks, he is sometimes found in the end to be unfit for service, and the trainer has to admit a new recruit in his place and start all over again. Often a dog can do certain tasks much better than others, and so each one is assigned to the kind of service which he can do best.