730 NERVOUS SYSTEM. 



tions to the functions of nutrition, secretion, movements, etc., amounts to comparatively 

 little. The very name, sympathetic, is some indication of our indefinite ideas with regard 

 to its functions ; but we have adopted this name, for the reason that it is the one most 

 generally in use, although it has no very exact relation to the peculiar functions of the 

 system. It is sometimes called the ganglionic nervous system ; but this name is inappro- 

 priate, as it implies that it alone possesses ganglia. The name of the system of organic, 

 or vegetative life is more in accordance with its general functions ; but this is not so com- 

 monly used as that of sympathetic system. The older anatomists and physiologists called 

 the great cord of this system the nervus intercostalis. 



As far as we know, there is no account of the sympathetic system, even in the most 

 recent works upon physiology or in special treatises, a careful study of which does not con- 

 vey the idea that there is little else in the literature of the subject than controversial 

 questions of priority, etc., in minor details, and a few observations, some of them quite 

 unsatisfactory, with regard to the effects of the division or galvanization of sympathetic 

 filaments upon the functions of circulation, secretion, and animal heat. It is unfortunate 

 that well-ascertained facts, which might be stated in a very few pages, should be so 

 largely overshadowed by a mass of purely historical details of no great interest. Still, we 

 must take the physiological data as we find them and endeavor not to limit the knowledge 

 to be looked for in the future, by adopting theories upon insufficient positive evidence. 



There are certain important anatomico-physiological questions, more or less definitely 

 determined, that have a direct bearing upon the functions of the sympathetic system. 

 These are the following : Is the sympathetic anatomically and physiologically dependent 

 upon its connections with the cerebro-spinal nerves ? What are the general properties 

 of the sympathetic nerves as regards motion and sensation? Do the sympathetic ganglia 

 act as independent reflex nerve-centres? To what extent and in what way do the sym- 

 pathetic ganglia and nerves influence the functions of the various organs and tissues to 

 which their filaments are distributed ? A solution of these questions involves a careful 

 and critical study of the results of experiments upon living animals and of pathological 

 facts; and it is evident that very little information is to be derived from observations 

 made anterior to the discovery of the properties and functions of the most important 

 parts of the cerebro-spinal system. We shall begin the study of these points with an 

 account of the general arrangement and the peculiarities of structure of the sympathetic 

 ganglia and nerves. 



General Arrangement of the Sympathetic System. 



Like the cerebro-spinal system, the sympathetic is composed of centres and nerves, 

 at least as far as we can judge from its anatomy. The centres contain nerve-cells, most 

 of which differ but little from the cells of the encephalon and spinal cord. The nerves 

 are composed of fibres, the greater part of which are nearly identical in structure with the 

 ordinary motor and sensory fibres. The fibres are connected with the nerve-cells in the 

 ganglia, and the ganglia are connected with each other by commissural fibres. These 

 ganglia constitute a continuous double chain, on either side of the body, beginning above, 

 by the ophthalmic ganglia, and terminating below, in the ganglion impar. It is important 

 to note, however, that the chain of sympathetic ganglia is not independent, but that each 

 ganglion receives motor and sensory filaments from the cerebro-spinal nerves, and that 

 some filaments pass from the sympathetic to the cerebro-spinal system. The general dis- 

 tribution of the sympathetic filaments is to mucous membranes and possibly to integu- 

 mentto non-striated muscular fibres, and particularly to the muscular coat of the 

 arteries. As far as we have been able to learn from anatomical investigations, there are 

 no fibres derived exclusively from the sympathetic which are distributed to striated 

 muscles, except those which pass to the muscular tissue of the heart. Near the terminal 

 filaments of the sympathetic, in most of the parts to which these fibres are distributed, 

 there exist numerous ganglionic cells. 



