To study the laminated structure of the lens, it is best to boil the lens. The best way to do that is to drop the lens from either a hardened or unhardened eye into boiling water. Let it boil in the water for about two and a half to three minutes. Longer than that time will cause the lens to be put out of shape, and make it so fragile that it can no longer be handled without having it fall apart. If the lens comes from an unhardened eye it might be best to boil it not more than about two minutes. [Illustration: Fig. 19--Showing the way the onion-like layers of the lens may be peeled off.] Insert the point of the scalpel carefully at one of the poles, and lift gently in the direction of one of the radiating lines. This will tend to raise one of the concentric layers, which can be easily peeled off. Repeat this in the direction of the other two radiating lines. Examining, with a hand lens, the exposed surfaces and the layers, as they are taken off, will show the arrangement of the lens fibres, and will also show plainly their directions. (Fig. 19.) To get another view of the onion-like layers of the lens, cut through it with a safety-razor blade, either longitudinally or equatorially. (Fig. 20.) The better way is to have enough lenses to make one of each kind. Never try to work with only one piece of material. If the lens is first stained with chromic acid the layers may be seen better, or, a simpler way is to drop the lens, before cutting it in two, into a carmine solution; red ink slightly diluted, will do. [Illustration: Fig. 20--Section through lens showing its concentric layers.] A lens that has been boiled and partly dissected may be placed in a 5 per cent. formaldehyde solution, and kept indefinitely. The lens fibres, concentric layers, and lens laminae in such a specimen will always be interesting.