An American Physiologist Abroad:
Francis Gano Benedict’s European Tours

1. Nutrition Science

Nutrition emerged as a special field of physiology in Germany in the late 1850s, when three former pupils of Justus Liebig – Carl Voit, Theodor Bischoff and Max Pettenkofer – began studying the metabolism of dogs and humans. Their experiments cast doubt on the established nutrition theory of Liebig, and they introduced precision measurement, analysis and apparatus, the methods of the new German physiology, into nutrition and metabolism research. In the 1880s, a pupil of Voit’s, Max Rubner, finally proved what Emil Du Bois-Reymond, Hermann von Helmholtz and their circle of physiologists had been proclaiming since the 1840s – that the energy conservation law applied to living organisms, or, at least, to dogs.

By the 1870s, physiology was an apparatus-based discipline. It required instruments that could rarely – if at all – be found in the United States and training in the skills to use them. American students of chemistry, physiology and medicine had long flocked to the well-equipped and established laboratories and universities of Germany for basic and specialized training. Central instruments for metabolism research were the respiration apparatus of Voit and Pettenkofer, which measured metabolism indirectly through measuring carbon dioxide production; the animal calorimeter, which measured the body’s heat production; and, after Rubner’s experiments, the combined respiration calorimeter, which measured all of the body’s input and output. The laboratories of Rubner and Voit in Berlin and Munich became popular destinations for medical students and physiologists interested in learning about the latest metabolism research and how to build and use its complex apparatus.