“…The question is open as to whether the substances immediately affect the vessels. 'Reflectory vasomotory changes in the hand are effected by vasoconstrictor nerves; vasodilator nerves are, if existing, relatively unimportant' [7, see also (4,14,23,25]. Consequently the increase of the cutaneous circulation in the hand is based not on active vasodilatation but on the decrease of the vasoconstrictor tonus.…”