Like de Bordeu, and more definitely, Legallois anticipated the conception of internal secretions. He surmised from the identity in composition of all varieties of arterial blood and the diversity of venous blood in different parts of the body, that this diversity is acquired, in each case from the loss of some substance from the organ from which the vein proceeds.

Le Gallois described the action of the vagus nerve on respiration. He showed that bilateral section of the vagus can produce fatal bronchopneumonia. The above work includes (p. 37) his location of the respiratory center in the medulla , and not in the spinal cord, as had been previously believed. “For the first time, an area of brain substance within a major subdivision of the brain and having a specific function had been defined accurately by experiment” (Clarke & Jacyna).

Le Gallois is also remembered for his reviving, after Borelli, the neurogenic theory of the heart’s action; namely that the motor power of the heart comes from the spinal cord via branches of the sympathetic nerves. Le Gallois also developed a primitive isolated heart-lung preparation in rabbits and was the first to suggest the possibility of a heart-lung machine: “If the place of the heart could be supplied by injection, and if, for the regular continuance of this injection, there could be furnished a quantity of arterial blood, whether natural or artifcially formed . . . then life might be indefnitely maintained” (quoted in Fye, “Julien Jean César Legallois,” Clinical Cardiology 18 (1995): 599-600. . Digital facsimile of the 1812 edition from the Internet Archive at this link. English translation by N. C. and J. G. Nancrede (Philadelphia, 1813) as Experiments on the principle of life, and particularly on the principle of the motions of the heart, and on the seat of this principle: including the report made to the first class of the Institute, upon the experiments relative to the motions of the heart. Digital facsimile from the Medical Heritage Library, Internet Archive at this link.