522 SYSTEM OF THE GREAT SYMPATHETIC. 



Occasionally, however, they last for a long time. Bernard (op. tit.) 

 has seen the unnatural temperature of the affected parts remain, in 

 the rabbit, from fifteen to eighteen days, and in the dog for two 

 months. Where the superior cervical ganglion has been extirpated, 

 he has even found the above appearances to continue, in the dog, for 

 a year and a half. They may also, according to the same authority, 

 be reproduced several times in the same animal, by repeated divi- 

 sions of the sympathetic nerve. 



The above effect is due to a peculiar modification in the nutri- 

 tion of the affected parts, which has some analogy with inflamma- 

 tion. The unnatural heat, the congestion, and the increased sensi- 

 bility which are present, all serve to indicate a certain resemblance 

 between the two conditions. None of the more serious consequences 

 of inflammation, however, such as oedema, exudation, sloughing or 

 ulceration, have ever been known to follow from this operation ; 

 and the term inflammation, accordingly, cannot properly be applied 

 to its results. 



Division of the sympathetic nerve in the middle of the neck 

 has also a very singular and instantaneous effect on the muscular 

 apparatus of the eye. Within a very few seconds after the above 

 operation has been performed upon the cat, the pupil of the cor- 

 responding eye becomes strongly contracted, and remains in that 

 condition. At the same time the third eyelid, or " nictitating mem- 

 brane," with which these animals 

 167> are provided, is drawn partially 



over the cornea, and the upper 

 and lower eyelids also approxi- 

 mate very considerably to each 

 other; so that all the apertures 

 guarding the eyeball are very 

 perceptibly narrowed, and the ex- 

 pression of the face on that side is 

 altered in a corresponding degree. 

 This effect upon the pupil has 

 been explained by supposing the 



CAT,aftei section of the right sympathetic. circular fibres of the iris, Or the 



constrictors of the pupil, to be 



animated exclusively by nervous filaments derived from the oculo- 

 motorius ; and the radiating fibres, or the dilators, to be supplied 

 by the sympathetic. Accordingly, while division of the oculo- 

 motorius would produce dilatation of the pupil, by paralysis of 



