458 



Messrs. L. Hill and M. Flack. 



[May 29, 



the cribriform ligament cannot be pulled backwards so as to cause an 

 anatomical deepening of the angle. The ciliary muscle, however, by its 

 action opens up the supra-choroidal space and the meshes of the cribriform 

 ligament. " The circular sphincter fibres of the ciliary muscle move 

 inwards on accommodation and, straightening out the innermost fibres of the 

 cribriform ligament, allow the passage of aqueous into the supra-choroidal 

 space." Thomson Henderson has traced this passage by injections of Indian 

 ink. We maintain that the instantaneous transference of aqueous to and 

 from the front and the circumference of the lens is the essential part of the 

 act of accommodation. Without such transference the sphincter action 

 of the ciliary muscle could not take place : the semi-fluid exterior part of 

 the lens confined in its capsule bulges forwards in proportion as the aqueous 

 fluid is transferred from in front to the circumlental region. This is the 

 function which is subserved by the structure of the ciliary region and the 

 ciliary muscle, and the anatomical arrangements required to be re-examined 

 with this function in view. By the perfect-balanced action of the intra- 

 ocular fluids pressure is instantly transmitted, and the fineness and celerity 

 of the movements of accommodation are made possible. We suggest that certain 

 of the longitudinal fibres and the circular fibres are antagonistic in action, 

 and balance the to-and-fro movements of the fluid. Thomson Henderson 

 has suggested an antagonism of action, but in relation to the tension of the 

 suspensory ligament. The anatomical arrangement of the ciliary muscle 

 figured by Henderson would equally well subserve the movement of fluid 

 to and from the circumlental region. The manometric method shows no 

 change of pressure on accommodation because the lens bulges forwards in 

 proportion as the circumlental region swells. The delicate membrane 

 observed by Ulbrich gave evidence of the sudden pull of the muscle and its 

 action on the aqueous fluid. We opine that the shaking of the lens 

 observed by Hess results from the transference of fluid to the circumlental 

 region. This fluid affords a waterbed on which the lens can shake. 



In confirmation of the view which we have put forward we quote the 

 observation made by Beer, that accommodation through stimulation of the 

 ciliary muscle is no longer possible when a hole is cut into the posterior 

 wall of the eye so that the counterbalancing pressure of the vitreous is nil. 

 The sphincter action of the ciliary muscle depends on the counterbalancing 

 influence of the intraocular pressure ; the pressure of the vitreous gives an 

 equable support behind, while the ciliary muscle, by its sphincter action, 

 widens the meshes of the ciliary body and cribriform ligament, and draws 

 aqueous into the circumlental region. 



