THE SYMPATHETIC SYSTEM 303 



The vagus inhibits the cardiac contraction by means of 

 a central ganglionic neuron which goes from the bulb to 

 the ganglia of Wrisberg and a ganglion-splanchnic neuron 

 which goes from the ganglion of Wrisberg to the heart. 

 The sympathetic accelerates the heart by means of a 

 central-ganglionic cell which goes from the superior 

 portion of the dorsal cord to the star ganglion and from 

 there a ganglion-neuron w r hich reaches the heart. 



IV. THE VARIOUS NERVOUS SYSTEMS OF AUTONOMIC 



LIFE AS A WHOLE. 13 



From a morphological and physiological point of view, 

 going from the simple to the complex, we see that the 

 vegetative nervous system is composed as follows: 



1. Local systems. 



2. Central splanchnic systems connected with two 

 neurons, one a central ganglionic neuron, the other a 

 ganglion-organic neuron. 



3. A co-ordinating system, organic co-ordination, 

 animal co-ordination, organo-psychic co-ordination and 

 inversely. These systems are represented by association 

 medullary tracts or medullo cephalic tracts. Finally, in 

 the higher centres, the encephalo-encephalic associa- 

 tion tracts. 



How shall we group these various elements? All evi- 

 dence points to the fact that the local systems belong to the 

 organs w r hich they control; there is a local system for 

 the heart, for the stomach, for the intestines. It becomes 

 however, more complicated when we reach the central 

 splanchnic systems. Here one fact stands out promi- 

 nently and that is the very general character of the 

 distribution and control of the true sympathetic which 

 has been called vaso-dorsal by Gaskell. Another impor- 



13 See Figs. 25, 27 and 29. 



