110 ORIGINAL ARTICLES. 



the lids, projection of the bulb, retraction of the nictitating mem- 

 brane, 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 eye-ball, 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 

 that its reprojection by subsequent irritation was a reposition. Schiff 

 regarded the projection of the bulb as due to the action of the 

 obliqui : the movements of the lids he considered to be passi-\e, and 

 due to those of the bulb. 



Eemak, on the other hand, believed that the narrowing of the 

 palpebral fissure was due to a relaxation of the levator palpebra? supe- 

 rioris, accompanied by a spasmodic contraction of the orbicularis. 

 Moreover, he conceived that the sympathetic acted upon the volun- 

 tary muscles of the Hds about the eye. 



Muller considers that it is now no longer necessary to discuss 

 the various probabilities respecting the influence of the sympathetic 

 upon the voluntary muscles of the eye, as a complete series of unstriped 

 muscles have now been observed, which will serve as a foundation for 

 explaining the movements in question. 



These muscles consist of three divisions : — 

 1st. In the oi'bital cavity of mammals, a membrane (membrana 

 orbitalis), consisting of imstriped muscles with elastic tendons, exists, 

 which, by irritation of the cervical sympathetic, projects the contents 

 of the orbit, especially the bulb, forwards. Eetraction is produced by 

 the transversely-striped retractor. In man, the orbital muscle is 

 much reduced in size, and the retractor is wanting, so that a distiuct 

 projection of tlie bulb does not follow irritation of the symj)athetic, 

 as Wagner and H. Muller himself have observed. 



2nd. The projection of the nictitating membrane in mammals is 

 mostly due to the retractor bulbi under the influence of the N. 

 abducens. Its withdrawal depends on some unstriped muscles 

 which are under the influence of the sympathetic. In hares, how- 

 ever, the withdrawal is due to a transversely strij^ed muscle, which 

 is not supplied by the spnpathetic but by the oculo-motorius. In 

 man, the lid and its muscles are rudimentaiy. 



3rd. The upper and lower lid possess in man, and ia very many 

 mammals, unstriped muscles, which have the power of drawing them 

 back. They are more feeble in the upper thai) the lower lid, so that 

 by irritation of the sympathetic the latter is drawn back in a more 

 marked manner than the former. Narrowing of the palpebral fissure, 

 after section of the cervical syuipathetic, depends upon relaxation of 

 these nmscles. Yet recession of the eye-ball may depend upon 

 relaxation of the orbital muscle. Muller, then, concludes that the 

 movements occasioned by experimenting on the cervical sympatlietic, 

 are not such as to entitle us to infer an influence of that nerve upon 

 voluntary striped muscle. lie also considers that the movements 



