As years roll on, if the interest in Natural History has not diminished, the man, with increasing intelligence and scope of reading, masters the knowledge desired in his youth, and has the opportunity, should he care to grasp it, of the highest intellectual enjoyment. He can enter into the consideration and discussion of the mysterious problems of life: of its origin; of the reasons why animals differ; why they are distributed here and there, or limited in their position in the world; what connection there may be between those of the past and of the present, and of the relation between the creation and the Creator. Besides this, even should he not aim so high, the man who has had a slight training in Natural History often employs his knowledge for the benefit of art and commerce. How beautiful are the representations of animals on some old coins, how grotesque are those on others! Yet the most correct, and, therefore, the most beautiful, were the result of the careful study of Nature. What benefits to men have resulted from the production of certain breeds of horses, sheep, and oxen! But it has been the study of Nature, and of the laws of the powers of inheritance, which led to most of these results: and thus the practical man is dependent upon the student for his success. Notwithstanding the interesting nature of the study of the Natural History of Animals, there is certainly more interest taken in it during early life than later on. As a rule, men have no time for it, or they find that, after gaining a certain amount of knowledge, they must study hard if further progress is to be made. Moreover, the vast amount of useless things which had to be learned at school and college have no relation to Natural History, except, perhaps, to convey erroneous ideas and to teach fables, so that this important science has generally to be begun in earnest after the usual education has been completed. When the determination has been made to learn the Natural History of Animals, the student will have to study two separate, yet inter-dependent, branches of knowledge, namely, Zoology and Comparative Anatomy: for the one considers the external shape, habits, distribution, and classification of animals, and the other refers to their internal construction, anatomy, and physiology, and the relation which the internal parts bear to the external in the scheme of classification. These studies are evidently inseparable.