V IT LISM: A BRIEF HISTORICAL AND CRITICAL REVIEW. 231 Liebig standing alone when he proclaimed that in the living body chemical and physical forces acted under the influence of a non-chemical force or cause. So might he preach, but no physiologist would lend an ear. Eagerness for a unitary conception of living and lifeless nature called all to experi- ment and converted all to Mechanism. Moleschott, Vogt, Buchner (6) and Hiickel (7) hurried forth with views of the crudest materialism. In 1853 Rudolf Wagner was forced to cease his Physioloyische Brief e, so ill-received were his protests against materialism. His offer to meet Ludwig at the Gcittingen Congress of Physiologists in 1854 was frustrated (according to his own statement) by illness. Certainly it is said that not one physiologist out of 500 present raised his voice in favour of a special soul-substance. During the same year Wagner published his Glaube und ir/'.s-.scw, wherein he stated that as regards knowledge he followed the teachings of science, but that his faith he shared with the humblest charcoal-burner. This met Vogt's fiercely polemic reply which he entitled Kohlerglaube und Wissenschaft. Here the bitter fight ended, and with Rudolf W T agner the last of the ultra-vitalists passed away (8). Meanwhile in France, Claude Bernard was pursuing his famous researches, and bringing his critical acumen to bear in the final overthrow of eighteenth-century vitalism. He predicted the future assimilation and agreement of the vitalistic and mechanical theories of life (9), and, like his master Magendie, vehemently opposed the current doctrines of the Parisian school. Wagner's Handiuorterbuch der Physi- olocjie contains an introductory chapter by Hermann Lotze, entitled " Leben-Lebenskraft ". An examination of Lotze's views scarcely comes within the scope of this essay, but, if only because of their bold independence, they deserve passing mention here. Lotze is indeed a thorough-going mechanist so far as the a-psychical processes of life are concerned. But, like Descartes, he finds himself compelled to conclude that " the living animal body considered as a mechanism is distinguished from all other mechanisms by the posses- sion of a principle of immanent disturbances which in force and frequency follow no mathematical law" (10). This conception of a soul is developed to a marked degree in Lotze's later writings, where also the vigour of his attacks on vitalism is correspondingly diminished. In certain works he had hesitated to admit the rule of the soul (unconscious of the process by long habit) over meta- bolism and development (11). In after years, however, the peculiar relation which he held to subsist between Meta-