1873.] Mr. A. T. Norton on the Accommodation of Vision. 423 



The idea conveyed was, that two layers of spherules (first detected 

 by Mr. Beaumont within the tubes), like two confined layers of small 

 shot, had, by compression, been forced and largely spread out into broader 

 layers. It was thought also that detached portions resembled long 

 tubes or puckers filled with spherules exactly fitting them. The sphe- 

 rules appeared perfectly spherical, but somewhat unequal in size. 



In the general flattened and extended surface of the compressed and 

 disintegrated scale the spherules appeared dark blue or red, according to 

 the slight change in the focal plane, and in a still lower plane white. 



In the adjoining uninjured scales long strings of beads were seen, like 

 necklaces of coral, here and there sharply bordered with black lines, 

 apparently denoting tubes of membrane or puckers enclosing them like 

 a tube. Between these strings of spherules peeped forth others of a light 

 orange-colour. 



The slide was an old one and well known. The mass of the crushed 

 scale occupied a much broader space than any of the scales. 



XVIII. " On the Accommodation of Vision, and the Anatomy of 

 the Ciliary Body." By Arthur Trehern Norton, F.R.C.S., 

 Lecturer on Anatomy at St. Mary's Medical School. Com- 

 municated by Dr. Sibson, V.P.R.S. Received June 5, 1873. 



(Abstract.) 



This paper is to show that the increase in the convexity of the lens, 

 when accommodated for near vision, is effected by compression of the 

 equator of the lens by an erectile cushion composed of the ciliary pro- 

 cesses turgid with blood, the ciliary muscle being the motor agent ; also 

 that the iris aids accommodation by increasing its rapidity, but that 

 accommodation of vision can be effected slowly without the assistance 

 of the iris. 



The author states that, by dissection of human eyes, he has determined 

 the existence of an erectile mass attached to the interior surface of the 

 ciliary muscle from which the ciliary processes proceed, and that in dis- 

 sections of injected specimens the vessels of the ciliary processes and of 

 the erectile mass can be seen to pass through and between the fibres of 

 the ciliary muscle near to the apex of that muscle. 



Prom the festooned appearance of the ciliary processes when unin- 

 jected, and from their greatly increased size when injected, he concludes 

 that the ciliary processes, and the mass from which they project, are 

 erectile, and are capable of undergoing a great alteration in size, the 

 erection being due to compression of their veins by contraction of the 

 ciliary muscle. 



In the anatomy of the ciliary muscle he gives, as the origin of that 

 muscle, the middle fasciculus of the posterior elastic lamina of the cornea, 



2 l 2 



