Page:Popular Science Monthly Volume 71.djvu/551

As a student of the great French naturalist, Cuvier, he became an eloquent advocate of the existence in nature of four great branches of the animal kingdom. He was early convinced that branches, classes, orders, families and genera had as distinct an existence in nature as species, and his life work was to make clear and rigid their definition. His eager desire to understand the relations existing between obscure forms was expressed one day in a private talk to his pupils, when he earnestly exclaimed, "The lamprey eel has been my puzzle and my misery for twenty years."

Not only in many technical essays, but as an eloquent teacher, he made these principles of classification so plain that vast audiences were able to grasp his conceptions. Those who heard his lectures on the subject will never forget the vivid way in which he impressed upon his auditors these views emphasized by graphic blackboard drawings.

In his methods of study in Natural History he presented in a popular form the leading features of his belief in the systematic relations of animals as embodied in his famous "Essay on Classification." The following quotation from his Methods of Study will indicate the ideas which were surely preparing the ground for the acceptance of the theory of evolution:

Man is the crowning work of God on earth, but though so nobly endowed, we must not forget that we are the lofty children of a race whose lowest forms lie prostrate within the water, having no higher aspirations than the desire for food; and we can not understand the possible degradation and moral wretchedness of Man, without knowing that his physical nature is rooted in all the material characteristics that belong to his type and link him even with the fish. The moral and intellectual gifts that distinguish him from them are his to use or to abuse; he may, if he will, abjure his better nature and be Vertebrate more than Man. He may sink as low as the lowest of his type, or he may rise to a spiritual height that will make that which distinguishes him from the rest far more the controlling element of his being than that which unites him with them.

Not only by such expressions just quoted, but in other statements, he certainly prepared the way for the more prompt recognition of Darwin's views.

Inspired by the belief in the existence in nature of categories of structure, he strengthened old homologies and established many new ones. In representing the four Cuvierian branches by schematic lines, he did not draw a series of lines one above the other, or enclose each group by sharply defined brackets, but drew these lines, parallel it is true, but side by side in an ascending scale, slightly overlapping. He endeavored to indicate by such a diagram his belief, which was correct, that the higher members of a lower group were more advanced in structure than the lower members of a group next above. Thus while the vertebrates were higher as a branch than the articulates, the highest class of the articulates, the insects, were higher in structure than many