580 APPENDIX. 



orbital vessels proceed, and with which it is in immediate relation, and 

 the very abundant vascular network found in connection with it, point, 

 I think, to some special relation between the muscle and the vessels, a 

 relation which is not at all inconsistent with what is known of the 

 function of non-striped muscle in other localities. 



****** 



Note. Since the above paper was in type, my attention has been 

 directed by Professor Huxley, to a communication by H. Muller, dated 

 15th Dec., 1860, entitled "On the Influence of the Sympathetic upon 

 some Muscles, and on the extensive occurrence of Unstriped Muscles in 

 the Skin in the Mammalia." 



As this paper throws some additional light upon the probable action 

 of the orbital muscle, I append a short abstract of it : 



H. Muller, after referring to the many puzzling questions which have 

 arisen respecting the function of the sympathetic nerve, and its relations 

 to the muscles supplied by it, proceeds to ask two questions 



1st, Whether, and which, unstriped muscles are supplied by other 

 nerves than the sympathetic 1 



2nd, Whether, and which, transversely-striped muscles are under the 

 influence of the sympathetic ? 



In answer to the first, the action of the oculo-motor nerve upon the 

 unstriped fibres of the iris cannot be doubted ; the vagus also acts upon 

 unstriped muscles, and the experiments of Schiff have shown that the 

 greater part of the vascular nerves are not connected with the sympa- 

 thetic. 



The second question may be most effectually answered by considering 

 the effect produced upon the eyeball by division or irritation of the 

 cervical sympathetic. Muller, for this purpose, refers to the experiments 

 of Bernard R. Wagner, and Brown-Sequard ; the general tendency of 

 which is to show, that division of the cervical sympathetic produces 

 narrowing of the palpebral fissure, retraction of the bulb, projection of 

 the nictitating membrane and narrowing of the anterior nares and the 

 mouth. Irritation of the nerve by galvanisation, on the other hand, 

 produces increase of the opening of the lids, projection of the bulb, re- 

 traction of the nictitating membrane, relaxation of several facial muscles. 

 Respecting the causes which produced these changes there was some 

 difference of opinion. R. Wagner could scarcely conceive that any force, 

 save the contraction of the two obliqui, could produce projection of the 

 eyeball, and yet he asks, " How could these transversely-striped muscles 

 receive excito-motory fibres from the sympathetic?" Brown-Sequard, 

 again, considered that retraction of the bulb, after section of the nerve, 

 was produced by the active contraction of the retractor and recti, and 



