THE SYMPATHETIC SERVE. 575 



be more convenient to consider the ganglia now in connec- 

 tion with the functions that they may be supposed to 

 control, in the several organs supplied by the sympathetic 

 system alone, or in conjunction with the cerebro-spinal. 



The general processes which the sympathetic appears to 

 influence, are those of involuntary motion, secretion, and 

 nutrition. 



Many movements take place involuntarily in parts sup- 

 plied with cerebro-spinal nerves, as the respiratory and 

 other spinal reflex motions ; but the parts principally 

 supplied with sympathetic nerves are usually capable of 

 none but involuntary movements, and when the mind acts 

 on them at all, it is only through the strong excitement or 

 depressing influence of some passion, or through some 

 voluntary movement with which the actions of the involun- 

 tary part are commonly associated. The heart, stomach, 

 and intestines are examples of these statements ; for the 

 heart and stomach, though supplied in large measure from 

 the pneumogastric nerves, yet probably derive through 

 them few filaments except such as have arisen from their 

 ganglia, and are therefore of the nature of sympathetic 

 fibres. 



The parts which are supplied with motor power by the 

 sympathetic nerve continue to move, though more feebly 

 than before, when they are separated from their natural 

 connections with the rest of the sympathetic system, and 

 wholly removed from the body. Thus, the heart, after it 

 is taken from the body, continues to beat in Mammalia for 

 one or two minutes, in reptiles and Amphibia for hours ; 

 and the peristaltic motions of the intestine continue under 

 the same circumstances. Hence the motion of the parts 

 supplied with nerves from the sympathetic are shown to 

 be, in a measure, independent of the brain and spinal 

 cord. 



It seems to be a general rule, at least in animals that 



