"Naked life": the vital meaning of nutrition in Claude Bernard's physiology

The aim of this paper is to elucidate the vital meaning and strategic role that nutrition holds in Claude Bernard's  "biological philosophy", in the sense Auguste Comte gave to this expression, i.e. the theoretical part of biology. I propose that Bernard's nutritive perspective on life should be thought of as an  "interfield" object, following Holmes' category. Not only does nutrition bridge disciplines like physiology and organic chemistry, as well as levels of inquiry ranging from special physiology to the organism's total level, including the cell and protoplasm, but it also forms the genetic and structural foundation for Bernard's two fundamental axioms in general physiology: the necessary complementarity of destruction and creation (1) and the uniformity of this physiological law across all life forms, be it plants or animals (2). Because Bernard's nutritive theory is a major pivot for the re-ordering of life and its characterization, I argue that it must be located and understood in the scientific and metaphysical context of his time, of which he claims to be the heir and challenger-what I propose to characterize as the  "epistemic space" of nutrition, on the background of which Bernard builds his own  "logic". I then set out this logic of nutrition, focusing on three interrelated bernardian theses: the establishment of the theory of indirect nutrition as the basis for the notion of  "milieu intérieur"; the enduring conception of nutrition as a continuous generation; the emphasis on nutrition as a way of reshaping the form/matter relationship.

Heredity as a problem. On Claude Bernard's failed attempts at resolution

Heredity has been dismissed as an insignificant object in Claude Bernard's physiology, and the topic is usually ignored by historians. Yet, thirty years ago, Jean Gayon demonstrated that Bernard did elaborate on the subject. The present paper aims at reassessing the issue of heredity in Claude Bernard's project of a "general physiology". My first claim is that Bernard's interest in heredity was linked to his ambitious goal of redefining general physiology in relation to morphology. In 1867, not only was morphology included within experimental physiology, but it also theoretically grounded physiological investigations. By 1878, morphology and physiology were considered as completely independent sciences, and only the latter was perceived as suitable to experimentation. My second claim is that this reversal reflected the existence of two opposite attitudes towards heredity. In the late 1860s, Bernard was convinced that heredity would soon be accessible to experimental manipulation and that new species would be produced in the laboratory exactly like organic chemistry succeeded to do for raw bodies. Ten years later, he ascertained that this was impossible. My third claim is that Bernard was epistemologically ill-equipped to address the issue of heredity. Bernard was strongly committed to a general reasoning scheme that acknowledged only three categories: determining conditions, constant laws and phenomena. This scheme was a key factor in his successes as a physiologist who was able to capture new mechanisms in living bodies. Nonetheless, it also prevented him from understanding how time and history could be endowed with a causal action that cannot be reduced to timeless parameters.

Physicochemical Biology and Knowledge Transfer: The Study of the Mechanism of Photosynthesis Between the Two World Wars

In the first decades of the twentieth century, the process of photosynthesis was still a mystery: Plant scientists were able to measure what entered and left a plant, but little was known about the intermediate biochemical and biophysical processes that took place. This state of affairs started to change between the two world wars, when a number of young scientists in Europe and the United States, all of whom identified with the methods and goals of physicochemical biology, selected photosynthesis as a topic of research. The protagonists had much in common: They had studied physics and chemistry (although not necessarily plant physiology) to a high level; they used physicochemical methods to study the basic processes of life; they believed these processes were the same, or very similar, in all life forms; and they were affiliated with institutions that fostered this kind of study. This set of cognitive, methodological, and material resources enabled these protagonists to transfer their knowledge of the concepts and techniques from microbiology and human biochemistry, for example, to the study of plant metabolism. These transfers of knowledge had a great influence on the way in which the biochemistry and biophysics of photosynthesis would be studied over the following decades. Through the use of four historical cases, this paper analyzes these knowledge transfers, as well as the investigative pathways that made them possible.