96 Eye. 



very brittle, but in chromic acid mixture it is much 

 tougher and can then be cut in strips and several frozen 

 together in the microtome. Muller's fluid shows the 

 nervous structure best, chromic acid the connective 

 tissue. Good sections of the retina may be obtained 

 by cutting the whole eye of the frog, and it may be 

 double stained first. 



To do this, first place the whole eye in a strong solu- 

 tion of rosein until it is deeply stained, then wash away 

 the superfluous stain in methylated spirit, next place 

 the eye for a short time in strong solution of iodine 

 green and wash it well, soak in gum solution and freeze. 

 By this means very good sections can be obtained, the 

 granular layers having stained with the iodine green, 

 the others with rosein. 



They must be mounted in Canada balsam and should 

 not be left long in spirit. 



COKNEA. 



The cornea may be removed from an eye hardened 

 either in chromic acid mixture or in Muller's fluid, and 

 sections made with the freezing microtome ; they are 

 best stained with logwood. 



To demonstrate the Corneal Corpuscles and Nerves. 



Eemove the cornea from an animal just killed : this 

 is done by cutting round the margin with fine curved 

 scissors. Place the cornea in i per cent, solution of 

 gold chloride in the dark. Let it remain for from one 

 hour to one hour and a half for a guinea-pig, an hour 



