u6 



merited cells, the pars iridis retinae. The fibres of the 

 sphincter of the iris are seen in cross-section near its free edge 

 and posterior surface. Observe the ligamentum pectinatum, 

 composed of trabeculae of fibrous tissue uniting the ciliary 

 body to the outer coat at the -sclero-corneal junction. The 

 spaces between the trabeculae of this ligament communi- 

 cate with the anterior chamber, and are known as Fon- 

 tana's spaces. 



The ciliary body is a very much thickened portion of 

 the middle coat; it is continuous anteriorly with the iris, 

 and posteriorly with the choroid. It is composed of merid- 

 ionally placed folds, the ciliary processes, and the ciliary 

 muscle. The meridional fibres of this muscle have their 

 origin from the wall of the canal of Schlemm and the 

 adjacent fibrous tissue, extending backward to the anterior 

 portion of the choroid (the tensor choroidae), and into the 

 ciliary body. The equatorial or circular fibres of Miiller 

 are observed in cross section near the base of the iris. The 

 ciliary body and processes are covered by a double layer of 

 pigmented cells, the pars ciliaris retinae. Only a small 

 portion of the choroid is seen in this section. Note how 

 vascular it is. In the stroma many branched and pig- 

 mented connective tissue cells are seen. 



Notice how the coats of the retina are quite abruptly 

 reduced to a double layer of cells at the ora serata, contin- 

 uing over the ciliary body and posterior surface of the 

 iris as the pars ciliaris retinae and pars iridis retinae. 

 Observe the suspensory ligament of the lens, composed of 

 homogeneous fibres, these seemingly arising from the 

 apices of the ciliary processes, and passing from these to 

 the equator of the lens, some uniting with the capsule of 

 the lens on its anterior, others on its posterior surface. 



Draw this preparation as seen under low power. 



(b) Lens Fibres. 



A lens was macerated for several days in )^ % solution of 

 hydrochloric acid. Tease and mount in gum glycerine. 



Examine under high power. Sketch several of the 

 fibres, as seen under this power. 



