1. Soemmering (1818) appears to have been the unwitting (liscoverer of the yellow cornea. Of Esox he says (p. 71): "I have observed the aqueous humour to be beautifully yellow, in the living fish under water, the golden colour being easily distinguishable because of the colourlessness of the cornea and lens
2. describes a homogeneous pigmentation of the entire surface of the cornea in the sheep; the chromatophores were observed in sections, in all individuals studied. No observation was made of the fresh cornea, which may have been yellowish macroscopically. The breed of sheep was not mentioned, and the phenomenon is apparently restricted to certain breeds and probably fortuitous-at least, we failed to find chromatophores or free pigment in the fresh cornea of a Rambouillet ewe (ca. 1i years old). Although no pigment was seen, this cornea was distinctly cloudy-but not coloured;Cilimbaris,1910
3. The presence of numbers of rods at and near the edge of the macula may be a potent factor in this phenomenon. Rods have been held by many investigators to be capable of qualitative hue-perception at the short end of the visible spectrum,1931
4. There are some bright-light birds in which very few red droplets are present anywhere in the retina,1894
5. And see the excellent paper of Bailey and Riley (1931); these authors concluded that the parakeet Melopsittacus undulatus has essentially the same hue-discriminatory capacity as