47° APPENDIX. 



on a fresh specimen, if one is at hand. The changes in size and form 

 of the inipil can be observed in the Hving cat by changing it from a 

 light to a dark place and vice versa. 



Dissection. — Examine the internal structures on a preparation. 

 Then with fine scissors and forceps remove from the eye about one- 

 fourth of the wall, in the form of a quadrant having one point at the 

 optic nerve, the other at the centre of the cornea. 'I'he coats of the 

 eye can then be studied on the piece removed, while the other struc- 

 tures will be visible within the eyeball. No special directions are 

 necessary for observation of the structures described, unless it be the 

 capsule of the lens and the zonula ciliaris. The capsule of the lens 

 may be demonstrated by tearing a bit of it off with fine forceps. 

 The zonula ciliaris is easily seen by divaricating the edges of the cut 

 made in removing the quadrant, so as to stretch the fine fibres of 

 which the zonula is formed. 



II. The Ear (p. 415). 



(The muscles of the external ear are of little practical importance, 

 and will doubtless usually be omitted.) 



(i) The External Ear. Read the description of the external ear 

 (p. 415), verifying it by examination and comparison of an ear still 

 covered with integument, in the natural condition, and of a prepara- 

 tion of the isolated cartilages of the ear (Eig. 168). The latter may 

 be obtained by dissecting the skin and muscles from a fresh ear. 



(2) The scutiform cartilage (p. 418) should be observed in the 

 natural position, and as isolated. 



(3) The muscles of the external ear (p. 418, and Eig. 169). 

 Those connecting the external ear with other parts of the head have 

 been studied in connection with the facial muscles. The remainder 

 will be studied on an external ear removed according to the direc- 

 tions given on page 435. 



Remove the integument from the convex surface of the auricle, 

 sufficiently to expose the entire extent of the muscles. 



1. ^]'he rotator auris. Transect. 



2. ""I'lie adductor auris superior (Eig. 169, 1). 



3. The adductor auris mecHus {-i). 



4. The transversus auriculae (Fig. 63, i^ p. 97). 



5. The auricularis externus (Eig. 169, 10). 



6. The helicis (I'ig. 169, i). To expose tliis it will be necessary 

 to remove the integument from along the cranial border of the inner 

 surface of the auricle. 



7. The antitragicus (Eig. 169, c). Remove the integument 

 farther if necessary. 



8. The tragicus medialis (Eig. 169, 5, 5'). 



9. The concha^us externus (Fig. 169, 9). 



(4) Remove the tympanic bulla and petrous bone from the rest 

 of the skull, by the use of bone-forceps and scalpel. Trim away all 



