524 SYSTEM OF THE GREAT SYMPATHETIC. 



apparatuses ; and it is certain that it also takes part in reflex actions 

 in which the cerebro-spinal system is at the same time interested. 

 There are accordingly three different kinds of reflex action, taking 

 place wholly or partially through the sympathetic system, which 

 may be observed to occur in the living body. 



1st. Reflex actions talcing place from the internal organs, through 

 the sympathetic and cerebro-spinal systems, to the voluntary muscles and 

 sensitive surfaces. The convulsions of young children are often 

 owing to the irritation of undigested food in the intestinal canal. 

 Attacks of indigestion are also known to produce temporary amau- 

 rosis, double vision, strabismus, and even hemiplegia. Nausea, and 

 a diminished or capricious appetite, are often prominent symptoms 

 of early pregnancy, induced by the peculiar condition of the uterine 

 mucous membrane. 



2d. Reflex actions taking place from the sensitive surfaces, through 

 the cerebro-spinal and sympathetic systems, to the involuntary muscles 

 and secreting organs. Imprudent exposure of the integument to 

 cold and wet, will often bring on a diarrhoea. Mental and moral 

 impressions, conveyed through the special senses, will affect the 

 motions of the heart, and disturb the processes of digestion and 

 secretion. Terror, or an absorbing interest of any kind, will pro- 

 duce a dilatation of the pupil, and communicate in this way a pecu- 

 liarly wild and unusual expression to the eye. Disagreeable sights 

 or odors, or even unpleasant occurrences, are capable of hastening 

 or arresting the menstrual discharge, or of inducing premature 

 delivery. 



3d. Reflex actions taking place through the sympathetic system from 

 one part of the internal organs to another. The contact of food with 

 the mucous membrane of the small intestine excites a peristaltic 

 movement in the muscular coat. The mutual action of the diges- 

 tive, urinary and internal generative organs upon each other takes 

 place through the medium of the sympathetic ganglia and their 

 nerves. The variations of the capillary circulation in different 

 abdominal viscera, corresponding with the state of activity or re- 

 pose of their associated organs, are to be referred to a similar nerv- 

 ous influence. These phenomena are not accompanied by any 

 consciousness on the part of the individual, nor by any apparent 

 intervention of the cerebro-spinal system. 



