Brown-Séquard and the discovery of the vasoconstrictor nerves

In August 1852, Brown-Séquard who had left Paris for Philadelphia at the beginning of the same year published in the Medical Examiner a description of the effects he observed in various animals after electrical stimulation of the distal part of severed cervical sympathetic chains. The blood vessels of the face and ear contracted and the temperature of the tissues decreased. After stimulation ceased, all the phenomena observed by Claude Bernard after sectioning the chain reappeared, especially vasodilation and hyperthermia. Brown-Séquard concluded that the sympathetic chain sends motor nerve fibres to many of the blood vessels of the head and that vasodilation followed by hyperthermia resulted from the section of these fibres. This view was challenged by Claude Bernard who had assumed the presence of "calorific" fibres in the sympathetic chain. The controversy between the two physiologists is related in the article.