APPENDIX. 581 



that its projection by subsequent irritation was a reposition. Schiff 

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

 the movements of the lids he considered to be passive, and due to those 

 of the bulb. 



Remak, on the other hand, believed that the narrowing of the palpe- 

 bral fissure was due to a relaxation of the levator palpebrae superioris, 

 accompanied by a spasmodic contraction of the orbicularis. Moreover, 

 he conceived that the sympathetic acted upon the voluntary muscles of 

 the lids about the eye. 



Mliller 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 orbital cavity of mammals, a membrane (membrana 

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

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

 the orbit, especially the bulb, forwards. Retraction 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 distinct projection 

 of the bulb does not follow irritation of the sympathetic, as Wagner and 

 H. Mliller 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, however, the withdrawal is due 

 to a transversely-striped muscle, which is not supplied by the sympa- 

 thetic but by the oculo-motorius. In man, the lid and its muscles are 

 rudimentary. 



Srd, The upper and lower lid possess in man, and in very many 

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

 back. They are more feeble in the upper than 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 sympathetic, depends upon relaxation of 

 these muscles. Yet recession of the eyeball may depend upon relaxa- 

 tion of the orbital muscle. MUller, then, concludes that the movements 

 occasioned by experimenting on the cervical sympathetic are not such 

 as to entitle us to infer an influence of that nerve upon voluntary 

 striped muscle. He also considers that the movements about the nose 

 and mouth, said by Bernard to be produced by section of the sympathetic. 



