Take, again, the group of stories which I have labelled Purchasing Dogs. One sample of this kind might, as I have noted above, be put off as a case of imperfect observation, or as a curious coincidence; but when we get a whole group of stories it becomes very difficult to doubt that dogs may learn the first principles of the science of exchange. The Italian dog (page 59) which did the narrator a service by fetching him cigars, demanded payment in the shape of a penny, and then used that penny by exchanging it for a loaf, was far advanced in the practice of Political Economy. He not only understood and acted on an implied contract, but realised the great fact at the back of the currency. "What are guineas," said Horne Tooke, "but tickets for sheep and oxen!" The Italian dog did not, like a savage, say, "What is the use of copper to me, I cannot eat it?" Instead, he perceived that the piece of copper was a ticket for bread. It should be noted too that this dog, the dog called Hardy (page 57) and others, were able to distinguish between the pieces of copper given them. Again, the Glasgow story (page 53) shows that a dog can learn to realise that a halfpenny will buy not merely one thing but several things--in fact, that the great advantage of exchange by currency over barter is that it gives you a choice. While on the subject of purchasing dogs, it is curious to reflect how very little is wanted to convert the dog that is able to purchase into a free agent. If a dog can exchange his faculty for cigar carrying or his tricks against half-pence, why should he not exchange useful services, such as guarding a house or herding sheep, and so become self-supporting? Imagine a collie paid by the day, and, when his work was over, receiving twopence and going off to buy his supper. But the vista opened is too far-reaching. One sees down it dogs paid by the hour and by the piece, and then dogs asking for better pay and shorter hours, and, finally, dogs on strike, and dog "black-legs," or "free dogs." II.