478 



Mr. W. H. Jessop. 



[June 10, 



IV. " On the Anatomy, Histology, and Physiology of the Intra- 

 ocular Muscles of Mammals." By Walter H. Jessop, M.A., 

 M.B. Cantab., F.R.C.S., Demonstrator of Anatomy at St. 

 Bartholomew's Hospital, London, &c. Communicated by 

 Sir W. Bowman, Bart., F.R.S. Received June 7, 1886. 



(Abstract.) 



This research was prompted by the variety of opinions on the 

 snbjecfc of the histology, anatomy, and physiology of the intra-ocular 

 muscles. 



Owing to the wide range of the subject I have been obliged to 

 restrict myself almost entirely to the action of these muscles in 

 mammals. 



Most of the experiments have been on rabbits, dogs, or cats, and 

 numerous observations, especially on the histology and action of the 

 ciliary muscle, have been on human eyes. The animals experimented 

 on have always been completely anaesthetised. 



The subject has been divided into three chief parts — 

 I. The anatomy and histology ; II. The physiology ; III. The 

 action of cocaine, atropine and eserine, both singly and in combina- 

 tion. 



I. The anatomy of the intra-ocular muscles has been considered 

 as to (1) the muscular tissue, (2) the nerves, (3) the vessels. 

 (1.) The muscular tissue. 



A. The Iris consists of a sphincter muscle. 



This muscle in mammals is suspended to the ciliary border by a pos- 

 terior limiting membrane of elastic tissue. I have found no developed 

 dilator muscle extending from the pupillary to the ciliary border except 

 in rabbits, and in these animals it is very thin. Koganei says in the 

 otter, however, it is well developed. 



Any muscular fibres found are in the stroma of the iris in front of 

 the posterior limiting membrane. 



B. The ciliary muscle consists of unstriped muscle in mammals 

 attached by a tendon to the sclero-corneal junction, and its fibres 

 interlace by bundles in every direction, the most developed being the 

 radial and circular fibres, and the position of the ciliary body 

 determines the preponderance of so-called radial and circular fibres. 

 The author is inclined to think from the great variety in length and 

 development of the longitudinal fibres that they are chiefly attach- 

 ments of the muscle to the elastic tissue of the choroid, and may thus 

 correspond to the Fo-called radial fibres of the iris when they exist. 



(2.) The nerves proceeding to the intra-ocular muscles are branches 



