18i.« ' MICROSCOPICAL JOURNAL. 413 



Does the eye niipe.-ir to be [iioliile? Locate the parts that 

 show, viz: the pupil, the circular central opeuiug; theirs* 

 encircliii<i- the |iii|'il. silvery in color; the transparent 

 cornea, covt'iin^^- the juiiiil and iiis; l-eyond the cornea 

 enclosing the sides and back the white touj^h outer 

 sclerotic coat of the eye. Seize the eye firmly in the for- 

 ceps by the scifi-uiic coat and pull it out of the orbit, a* 

 you do this notice and cutaway the bands of //^wscZe whicli 

 attach it to the orbit, and at the back of the orbit notice 

 and cut tlie white cord optic nerve, which runs through: 

 the sclerotic cvit into the eye. Place the eye in clear 

 water and with a sharp knife or scissors split it in two 

 halves in a plane passing throujjjh the optic nerve, this- 

 will disclose: the anterior chamhtr of the eye, betweea 

 the cornea and the iris; the lar<:;er posterior chamber, be- 

 hind the iris; and inside the posterior chamber the spher- 

 ical lens. On the back of the eye inside the sclerotic 

 coat, the black choroid coat,\\\e vascular layer can be seen 

 anil inside this (in well })reserved specimens) the white- 

 retina. Repeat this dissection on the other eye; in re- 

 moving it from the orbit study the muscles that fastea 

 the eye- ball to the orbit and note that they are made of 

 fibers which by pulling roll the eye in its orbit, they are 

 not here sub-divided (as in the skate) into the six muscles, 

 of the eye of the higher vertebrates. Draw a diagrain- 

 malic longitudinal section of the eye in place in the orbit 

 and show all these points. 



[5. The Eah, — is piesent in tcleosts, but there is no 

 external indication of its presence; it is located in a car- 

 tilage and bone c.-i})sule, on the side of the brain case 

 and at the hinder level of the iiead; it has three se7Jii-cir- 

 c?^Zar ca/iaZ.s like the higlier vertebrates, and there are 

 large calcareous structures otolith, in an additional cham- 

 ber, the vestibule; branches from the 8th cranial nerve 

 (auditory) go to the ear ou each side from the medulla 

 oblongata.] 



