In a previous investigation1 the sweat secretion of normal persons was studied with the aid of Minor's iodine and starch method. It was pointed out that sweat is secreted under the influence of the nervous system, in particular under that of the thoracolumbar portion of the sympathetic system. Hence, the sweating test is one of the most valuable objective methods of analyzing the sympathetic cutaneous innervation. There are several procedures by which sweating may be induced, but it was shown that for the study of sympathetic function only the "thermoregulatory" sweating produced by the application of external heat and the ingestion of fluids and acetylsalicylic acid give reliable and conclusive results.2
Before the sweating reactions are described, a review of the general anatomic relations of the sympathetic chain and its connections is necessary.2d According to the conception of Gaskell3 and Langley,4 the sympathetic system consists