The great merit of the nineteenth century, as far as our knowledge of the human frame is concerned, lies in the founding of two new lines of research of immense importance--comparative anatomy and histology, or microscopic anatomy. The former was intimately associated with human anatomy from the very beginning; indeed, it had to supply the place of the latter so long because the dissection of human corpses was a crime visited with capital punishment--that was the case even in the fifteenth century! But the many anatomists of the next three centuries devoted themselves mainly to a more accurate study of the human organism. The elaborate science which we now call comparative anatomy was born in the year 1803, when the great French zoologist Georges Cuvier (a native of Mömpelgard, in Alsace) published his profound _Leçons sur l'anatomie comparée_, and endeavored to formulate, for the first time, definite laws as to the organism of man and the beasts. While his predecessors--among whom was Goethe in 1790--had mainly contented themselves with comparing the skeleton of man with those of other animals, Cuvier's broader vision took in the whole of the animal organization. He distinguished therein four great and mutually independent types: Vertebrata, Articulata, Mollusca, and Radiata. This advance was of extreme consequence for our "question of all questions," since it clearly brought out the fact that man belonged to the vertebral type, and differed fundamentally from all the other types. It is true that the keen-sighted Linné had already, in his _Systema Natuae_, made a great step in advance by assigning man a definite place in the class of mammals; he had even drawn up the three groups of half-apes, apes, and men (_Lemur_, _simia_, and _homo_) in the order of primates. But his keen, systematic mind was not furnished with that profound empirical foundation, supplied by comparative anatomy, which Cuvier was the first to attain. Further developments were added by the great comparative anatomists of our own century--Friedrich Meckel (Halle), Johannes Müller (Berlin), Richard Owen, T. Huxley, and Karl Gegenbaur (Jena, subsequently Heidelberg). The last-named, in applying the evolutionary theory, which Darwin had just established, to comparative anatomy, raised his science to the front rank of biological studies. The numerous comparative anatomical works of Gegenbaur are, like his well-known _Manual of Human Anatomy_, equally distinguished by a thorough empirical acquaintance with their immense multitudes of facts, and by a comprehensive control of his material, and its philosophic appreciation in the evolutionary sense. His recent _Comparative Anatomy of the Vertebrata_ establishes the solid foundation on which our conviction of the vertebral character of man in every aspect is chiefly based.