78 

 THE ORGANS OF SPECIAL SENSE. 



LABORATORY WORK FOR THE WEEK. 



References : 

 Points for Quiz : 

 Laboratory Report : 



Due : 



Obtain from the delivery desk, (a) paraffin sections, 178, 179, 

 180, 183, 185 ; (6) collodion sections, 181, 182, 184. 



EYE. 



178. Eye. Pig. Section through the anterior quarter of the 

 eye-ball. Zenker's fluid ; paraffin ; sections fx. Stain with 

 heinatoxylin and picrofuchsin. 



This section will include cornea, iris, ciliary body (muscle and 

 processes), schlera, choroid and retina. Study well the structure of 

 each of these parts, observing the relation of (a) schlera and cornea, 

 (5) iris and choroid, (c) ciliary and sensory parts of the retina. 

 Note also the canal of Schlemm, ciliary arteries, sphincter of the 

 pupil. Is there any trace of the suspensory ligament of the lens ? 



179. Eye. Cat. Section through the posterior half showing 

 the entrance of the optic nerve. Zenker's fluid ; paraffin ; sections 



fi. Stain with hematoxylin and picrofuchsin. 

 This preparation is to illustrate the structure of the three coats 

 of the eye, the layers of the retina, and the relation of the optic nerve 

 to the eye-ball, especially to the retina, and should be studied to 

 afibrd demonstration of these points. 



180. Retina. Pig. Vertical section. ; paraffin ; 

 sections jx. Stain with 



In this section identify the layers of the retina already seen in 

 178 ; be sure you understand the real structure of the retina as re- 

 vealed by other methods, and the meaning of the layers brought 

 out by ordinary methods. Distinguish the rods and the cones ; re- 

 member which side of the retina faces outward, i. e., is toward the 

 other coats of the eye. What course would the sensory impulse 

 pursue in order to reach the optic nerve ? 



