570 FUNCTIONS OF THE CEREBRO-SPINAL NERVOUS SYSTEM. 



the Cranio-Spinal axis, which constitutes the ordinary line of action for im- 

 pressions having their origin in the necessities of the Organic or Vegetative 

 life of the individual. That the Will should have a certain degree of con- 

 trol over these movements, is necessary in order that they may be rendered 

 subservient to various actions which are necessary for the due exercise of 

 Man's psychical powers; but that they should not be left dependent upon 

 its exercise, and should even be executed in opposition to it when the wants 

 of the system imperatively demand their performance, constitutes a wise 

 provision for securing Life against the chance of inattention or momentary 

 caprice. 



460. The Cerebro-SpinaJ system is intimately blended with another set of 

 ganglionic centres and nerve-trunks, scattered in different parts of the body, 

 but mutually connected with each other; this is commonly termed the sym- 

 pathetic system; but not unfrequently, from the position of its principal 

 centres, and their evident functional relation to the apparatus of Organic 

 life, the Visceral system. To this system we are probably to refer, not only 

 the Semilunar and Cardiac ganglia (which seem to be its principal centres), 

 with the chain of cranial, cervical, thoracic, lumbar, and sacral ganglia, 

 which are in nearer connection with the Cerebro-spinal system ; but also 

 numerous minute ganglia, which are to be found on its branches in various 

 parts. Moreover, the ganglia upon the posterior roots of the Spinal nerves, 

 and those upon the roots and trunks of certain Cranial nerves, may be 

 ranked with considerable probability und^r the same category; and if such 

 be the case, those fibres contained in the Cerebro-spinal nerves, which have 

 these as their ganglionic centres, must also be accounted as belonging to the 

 Sympathetic system. On the other hand there unquestionably exist numer- 

 ous fibres in the Visceral system, which proceed into it from the Cerebro- 

 spinal system ; these, however, are not uniformly distributed, for some of the 

 Visceral nerves contain few or none of them, whilst in others they are 

 numerous. The branches by which the Sympathetic system communicates 

 with the Cerebro-spinal, and which were formerly considered as the roots of 

 the Sympathetic system, seem to contain fibres of both kinds; i. e., Cerebro- 

 spinal fibres passing into the Sympathetic, and Sympathetic fibres passing 

 into the Cerebro-spinal. The latter are chiefly, if not entirely, transmitted 

 into the anterior branches of the Spinal nerves; the posterior branches being 

 apparently supplied with sympathetic fibres from the ganglia on their own 

 posterior roots. Some of these last fibres also pass from the Cerebro-spinal 

 into the Sympathetic system. By these communications, the two systems of 

 fibres are so blended with each other, that it is impossible to isolate them. 

 The branches proceeding from the Semiluuar ganglia are distributed upon 

 the vessels of the abdominal viscera; and those of the Cardiac ganglia upon 

 the heart and vessels proceeding from it. The latter seem to accompany the 

 arterial trunks through their whole course, ramifying minutely upon their 

 surface; and it can scarcely be doubted that they exercise an important 

 influence over their functions. What the nature of that influence may be, 

 however, will be a subject for future inquiry (chap. xvii). It is so evi- 

 dently connected with the operations of nutrition, secretion, etc., that the 

 designation, "nervous system of organic life," as applied to this system, does 

 not seem objectionable, provided that we do not understand it as denoting 

 the dependence of these functions upon it. The interpenetration of the 

 Cerebro-spinal system by the Sympathetic is strongly marked by these two 

 circumstances, that, in some of the lower Vertebrata, the distribution of 

 their trunks cannot be separately distinguished; and that, even in the 

 highest, some of the Glands, of which the secretion is most directly influenced 

 by the condition of the mind, are supplied with most of their nerves from 



