Physiologists explain this spontaneous movement of the heart as due to the ganglia in its substance. This explanation, which is founded on what I cannot but regard as a purely imaginary view of the functions of ganglionic cells, must stand or fall with that hypothesis. A long and arduous investigation has led me to doubt whether in _any_ case the heart’s movements are primarily due to its ganglia; at all events, the same spontaneous movements are observed in the hearts of molluscs and crustaceans, which are without even a trace of ganglia; and in the hearts of mammalian embryos long before ganglia or nerve-fibres make their appearance. Not less certain is it that movements of contraction and dilatation are produced in the blood-vessels independently of all central influence. This has been decisively proved by the Italian physiologist, Mosso, when experimenting on an organ isolated from the organism; and although the vessels have their nerve cells and fibres, he justly doubts whether it is to these that the stimulation is due, because the phenomena are observed after the nervous vitality has disappeared. Goltz severed all the tissues in the leg of a rabbit, so that the only connection of the leg with the rest of the body was through the crural vein and artery, which kept up the circulation; yet although the nerves of the skin were thus separated from their centre, so that no sensation could be produced by stimulating the skin of the leg, consequently no reflex from the centre on the vessels, Goltz found that a marked reddening of the skin from congestion of the capillaries followed the application of mustard to the skin. Physiologists who believe that the constriction and dilatation of blood-vessels are due to the action of the ganglionic cells distributed over the walls of the vessels will explain Goltz’s observation as a case of reflex action; but those who agree with me that such an hypothesis respecting the part played by the cells is untenable, will class the observation among other cases of direct stimulation.
95. But passing from these perhaps questionable cases, let us glance at other cases. The mobile iris of the bird displays movements after the nerves have been divided. Even the voluntary striped muscles are not altogether motionless. Schiff divided the hypoglossus on one side, and found, of course, the tongue paralyzed on that side; but he also found that on the third day after the operation some of the muscles of that side were quivering: the agitation spread to others, till by the end of the fourth day all the fibres were _rhythmically_ contracting. From this time onwards, the contractions were incessant; though they were never able to move the tongue, because the fibres did not contract simultaneously.