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Biol Bull 111: 375-386. (December 1956)
© 1956 Marine Biological Laboratory
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SELECTIVE LIGHT ABSORPTION BY THE LENSES OF LOWER VERTEBRATES, AND ITS INFLUENCE ON SPECTRAL SENSITIVITY

DONALD KENNEDY 1 and ROGER D. MILKMAN 1

1 The Biological Laboratories, Harvard University; Marine Biological Laboratory; and U. S. Fish and Wildlife Service Laboratory, Woods Hole, Mass.

1. Spectrophotometric studies of fresh intact lenses from a variety of fish and from frogs have shown that they are steep cut-off fibers for ultra-violet radiations, selectively absorbing almost all light of wave-length shorter than 400 mµ.

2. Certain species of fish possess lenses having high transmission in the near ultra-violet, between 320 and 400 mµ; these species must be sensitive to this spectral region, since visual pigments absorb there. Lenses of the butterfish show a steep cut-off at about 350 mµ.

3. There appears to be a correlation between possession of ultra-violet filtering lenses and a requirement for acute vision, supporting the idea that they aid visual acuity by eliminating wave-lengths which produce severe chromatic aberration. Such lenses, however, cannot be regarded as functionally equivalent to such intra-ocular carotenoid filters as retinal oil droplets and macula lutea since they absorb in quite different spectral regions. The theory that lens filters are an evolutionary "replacement" for oil droplets in secondarily diurnal animals is thus not in agreement with these findings.

4. Substances responsible for the properties of these lenses as filters have been extracted with water from the lens tissue. Lenses which cut off at 400 mµ yield a substance with an ultra-violet absorption maximum at 360 mµ; those of the butterfish, which cut off at 350 mµ, yield a substance with maximum absorption at 320 mµ. A presumed oxidation product of 360-pigment has been obtained which is spectrally similar to 320-pigment from the butterfish. Both substances have been characterized as to solubility, ultra-violet absorption spectra, and chromatographic behavior, but no definite identification has been made.

5. Comparison of spectral sensitivity in normal frogs and frogs deprived of their lenses has been made by recording the electroretinogram. The results show that the lens has the anticipated effect in restricting short-wave-length sensitivity. In frogs without lenses, scotopic sensitivity is in good agreement with the absorption of rhodopsin down to 360 mµ, while in normal animals sensitivity declines sharply below 400 mµ.




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T. Goldsmith
Hummingbirds see near ultraviolet light
Science, February 15, 1980; 207(4432): 786 - 788.
[Abstract] [PDF]


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Copyright © 1956 by the Marine Biological Laboratory.