milk-making machines, and has deprived the bulls of the greater part of their ancient savage humor. Owing to this change in the quality of their associates in captivity the dogs have also been led into great variations. The same type of interaction may be traced again and again in the isolated part of the world enclosed within our fences, as well as in the free realm of the wildernesses. All the individuals in the great host of life affect each other as do the soldiers of a well-organized army in the movements of a battle. The shepherd-dog, the turnspit, and the bull-dog are the three remarkable variations of the canine blood which were brought about by a process of training and selection unconsciously directed to the institution of breeds suited to special economic ends. The other varieties of dogs have been shaped more distinctly for purposes of amusement or for the indulgence of mere fancy. The several varieties of hounds, harriers, beagles, pointers, setters, terriers, etc., have been designed to meet a dozen or more variations in the conditions of the chase. The marvellously complete way in which special peculiarities have been developed in mind and body makes this field of domestic culture the most fascinating subject of inquiry to the naturalist. The ordinary fox-hound has had his inheritances determined so as to fit him for pursuing a small animal which can rarely be kept in view during its flight, and which can only be followed by the odor it leaves in its trail, so these creatures run almost altogether under guidance of their sense of smell. The stag-hound, on the other hand, pursues a relatively large animal which cannot well be followed by the nose, at least with any speed; they therefore trust almost altogether to vision in their chase. The packs which hunt otters have developed the swimming habit and an array of instincts which fit them especially for this peculiar sport. If space allowed we could note at least a dozen divisions of the group of hounds or chasing dogs, each of which has developed a peculiar assemblage of qualities, more or less precisely adapted to some particular game. [Illustration: Fox-Hound and Pups]