408 JAMES ROLLIN SLONAKER 



into a number of branches and supply the greater part of the 

 chorioid (fig. 25). The long ciliary nerves; after piercing the 

 sclera as a single branch just posterior to the optic nerve, divides 

 into two parts, which run forward in grooves on the surface 

 of the chorioid on the temporal side of the eye to the ciliary 

 region (fig. 26) . Here they turn almost at right angles to their 

 anterior course, one running dorsally and the other ventrally^ 

 to encircle the eye. In their course around the eye they are 

 unbedded in the ciliary muscles about midway of their length. 

 They give off numerous branches to these muscles, to the iris, 

 and to the ciliary processes, forming a close plexus of nerve- 

 fibers. All of these ciliary nerves are very much flattened in 

 their course over the surface of the chorioid. The grooves in 

 which they lie, therefore, are shallow and inconspicuous in cross- 

 section. 



In a preserved sparrow eye the sclera separates very freely 

 from the chorioid except at a few places, where the blood-vessels 

 and nerves pierce the sclera and enter the chorioid, binding the 

 two layers together. Another region of close attachment is 

 near the ora serrata. Here the posterior tendmous extension of 

 the muscles of accommodation is rather firmly attached to the 

 sclera. This is seen in fig. 33, which represents the posterior 

 portion of the ciliary muscle and its tendinous continuation. 

 An abnormal sepaiation of the chorioid and retina from the 

 sclera has occurred. There appears to have been a firmer at- 

 tachment of the tendon at its posterior end to the sclera than to 

 the chorioid (at T). Farther forward the attachment to each of 

 these layers is so strong that the muscle and tendon fibers have 

 been pulled apart instead of separating from the chorioid or the 

 sclera. The significance of this will be discussed in dealing with 

 accommodation. 



A short distance anterior to the ora serrata the chorioid is 

 modified to fonn the ciliary processes. These vary in number 

 from 70 to 75, the average being 72. These processes are com- 

 pletely covered on the inner surface by the pars ciliaris retinae. 

 The inner columnar cells of this layer are so thin in this region 

 that the pigment portion is very conspicuous. The surface of 



