412 JAMES EOLLIN SLONAKER 



separate from either the chorioid or sclera. The posterior 

 extremity of the tendon, however, shows a firm union with the 

 sclera and a separation from the chorioid. We may infer that 

 the separation took place at the weakest place. From this I 

 conclude that the two attachments of this muscle are to the 

 sclera as above stated. This conclusion is opposed to that of 

 many other writers. Leuckart ('76) and others claim that the 

 posterior attachment of the ciliary muscles is to the chorioid. 



According to many authors the ciliary muscles of the bird are 

 composed of three parts: Briicke's muscle, Miiller's muscle, and 

 Crampton's muscle. In the sparrow all of the fibers of the cil- 

 iary muscles run in the same general direction and are practically 

 parallel with each other. A division into these three groups was, 

 therefore, not accomplished. Their location, however, is shown 

 in figures 4 and 30. 



Accommodation in the bird is accomplished, in my opinion, 

 in a different manner from that in man. Because the center of 

 the lens, owing to its structure and great firmness, most prob- 

 ably cannot be changed in shape as in man, accommodation 

 must be accomplished in some other manner. Since both the 

 ends of the muscles of accommodation are attached to the 

 sclera, its contraction would draw its two attachments nearer 

 each other or exert a compressing influence on the sclera between 

 the attachments. This would necessarily tend to bend or buckle 

 the intervening part of the sclera. The fact that the scleral 

 plates have been found in various degrees of bending indicates 

 that the buckling of the sclera occurs in that region. The effect 

 of this tension is as follows: The equatorial diameter will be 

 reduced, resulting in increased intraocular pressure. This will 

 cause an increase in the axial diameter and will push the cornea 

 and lens farther forward, at the same time producing a greater 

 curvature of the cornea. These conditions make distinct vision 

 of a near object possible. 



When the muscles of accommodation relax, the elasticity of 

 the scleral plates would cause the sclera to spring back to its 

 former shape and the cornea to assume its original position. 

 The intra-ocular pressure back of the lens would be reduced, 



