EMBRYOLOGY
As a result of all these means and methods of study, and as a part of the great educational and scientific movement of the century, medical men now take a wholly different view of the normal and abnormal structures of the human body. The study of embryology has shown us that many of the deviations from the normal development of the human body are easily explained by embryology. One of the most important changes in our idea, for example, of tumors is due to the fact that the study of embryology and of the tissues of the embryo have shown us that diseased structures, which lack explanation entirely, when compared with the adult human tissues, readily find their explanation and fall into an unexpected order when compared with the tissues of the embryo. Not only, however, has the study of embryological tissues thrown a flood of light on diseased structures, but we have obtained new views of the relation of man to all creatures, lower in the scale of life. Largely owing to the doctrine of evolution, we now recognize the fact that, so far as his body is concerned, man is kindred to the brutes; that his diseases, within certain limitations, are identical with similar diseases of the lower animals; that his anatomy and physiology are, in essence, the same as the anatomy and physiology of the lower animals, even the very lowest, and that many of his diseases can be best studied in the lower animals, because upon them we can make exact experiments which would be impossible in man. While it is true that each animal has disorders which are peculiar to itself, and that it is not subject to some of the disorders to which man is a victim, and, per contra, that man is a victim to some disorders from which animals do not suffer, yet, taking them as a whole, the diseases of man and of animals, and the action of remedies on both, are practically identical. To this I shall have occasion to refer again.