Fig. 21.
A. Lens hardened in formaldehyde.
B. Lens hardened in formaldehyde, run through the alcohols, and cleared in xylol.
C. Lens hardened in formaldehyde, run through the alcohols, and cleared in cedar oil.
D. Boiled lens.
The longer a lens is left in either of these two clarifying fluids the harder and smaller it will become. At the end of a month or six weeks the lens will have become so hard that it can no longer be cut through with a knife. If it is desired to halve it, a scroll saw will be found to be the best thing to use for this purpose. ([Fig. 21].)
[3] “Anatomy and Physiology of the Eye,” Brown & Zoethout.
THE CHOROID
Select an eye that has had a long part of the optic nerve left on it and place it into a 5 per cent. solution of formaldehyde. Leave it in that solution for from two to three weeks. That period of time in the fluid will be sufficient to permit the choroid to become sufficiently toughened and hardened. Leaving it in the solution longer than that length of time will not injure the eye in any way.
Fig. 22—Showing how to puncture the cornea. (Page 62.)