how formed, [17]-18, [28];

images in, [175]-176;

as camera, [176];

and color, [177]-179, [183]-185;

object of two, [185]-186;

blind spot of, [186]-188;

of ants, [197]-200;

of various creatures, [214]-215, [219];

of insects, [215]-217;

black, [300] and following;