III. The Human Eye — Albinism

If we want to get into this matter, we must, above all, study the structure of the eye itself. Over time, I have told you many things about the eye. Therefore, today you will perhaps understand what I have to say. You see, the eye is located inside the very firm bony body of the head. The bone structure of the head bulges inside, and in this bone cavity, which is open towards the brain at the back (see drawing), the eye sits inside. The eye is now first limited from the outside by a hard skin, which is opaque here. The so-called eyeball is limited by the cornea. This skin becomes transparent towards the front, here, where it bulges out a little. Otherwise, one could not approach the light with the inside of the eye if this outer cornea were not transparent. It is called the cornea because it is horny. Inwards from this is a skin, which consists of fine veins. The blood network of the body extends into the eye and also sends very small, fine veins into the eye. So here we have the hard cornea, which becomes transparent towards the front, and then the so-called choroid, which is adjacent to it. The third skin inside is formed from nerves; this is the so-called retina. So I still have to draw a third membrane, the retina. And the retina goes backwards into the brain, as does the choroid, of course. And this is called the optic nerve because it is a nerve substance, it goes to the eye. You know that people say: you feel through the nerves. — So with the optic nerve you see.