THE FUNCTIONS OF THE NERVOUS SYSTEM. 265 



are more fully detailed in ray treatise on the Vital Functions. From them it 

 appears that although the muscles of voluntary motion obey a stimulus applied 

 to no part of the brain and spinal marrow but that from which their nerves 

 take their origin ; the heart is influenced by stimuli applied to eveiy part of 

 these organs, from the very uppermost surface of the brain and cerebellum to 

 the lowest portion of the spinal marrow. The same was found to be the case 

 with the blood-vessels to their minutest ramifications. Even the extremities of 

 the arteries and veins, where they unite to complete the circulation, it was 

 found by the aid of the microscope, could be influenced, nay even deprived of 

 power by agents whose operation was confined either to the brain or spinal 

 marrow. 



In some animals even of warm blood, as appears from experiments related 

 in my treatise on the Vital Functions, the motion of the blood in the capillaries 

 may be observed for an hour or even two hours after death, provided neither 

 great and sudden injury to the nervous system, nor great loss of blood be occa- 

 sioned by the mode of death ; that is long after the heart has ceased to beat. 

 The continued action of the capillaries appears from what is said in that treatise, 

 to be the cause of the large arteries being found empty some hours after death. 



It has also been shown by experiments detailed in the same treatise, an 

 account of some of which has appeared in the Philosophical Transactions, that 

 the stomach and lungs are in like manner under the influence of both the 

 brain and spinal marrow. 



The partial connection with the nervous system of the organs supplied by 

 the cerebral and spinal nerves, and the universal connection with that system 

 of those supplied by the ganglionic nerves, explain many of the phenomena, 

 both of health and disease. Why are aflfections of the stomach and other vital 

 organs felt instantly through every part of the frame, while the effects of those 

 of a muscle of voluntary motion, or even an organ of sense, although often a 

 part of greater sensibility, is confined to the injured part ? If the eye or ear, or 

 the muscle of a limb, be so deranged by a sudden blow, for example, as instantly 

 to destroy its power, sight, hearing, or the voluntary power of the part is 

 lost, and there the evil ends unless inflammation ensues ; but a blow on the 

 stomach, which instantly destroys its power, at the same moment destroys 

 that of every other part. It is not difficult to answer the question, since the 



MDCCCXXIX. 2 M 



