it was, he confined his theory to the idea of the "unity of type," making it the chief basis for his conception of evolution. In his own words, this theory enabled him to "assert, without hesitation, that all the more perfect organic natures, such as fishes, amphibious animals, birds, mammals, and man at the head of the list, were all formed upon one original type, which varies only more or less in parts which are none the less permanent, and which still daily changes and modifies its form by propagation."
Akin to Goethe, in some respects, was Gottfried Treviranus (1776–1837), a German naturalist who was a contemporary of St.-Hilaire, Goethe, and Lamarck. Like the German natural philosophers, he considered life as the result of chemical and mechanical processes, and protested whole-heartedly against purely speculative work, calling it "dreams and visions." At the same time, he complained that most of botany and zoology was made up of dry registers of names and that the work of many naturalists consisted of the "spirit killing * * * reading and writing of compilations." Treviranus believed that it was quite within the abilities of man to discover the basic philosophy of nature, largely by the use of working hypotheses as a means of aiding the investigator in attaining the actual facts.
In view of Treviranus' modern stand on the study of animal life, and the interpretation of ascertained facts, we might well expect him to show an equal modernity in his conception
