http://link.springer.com/content/pdf/10.1007/978-3-642-66907-1_4.pdf

Optics and Vision in Invertebrates

Structures that cause colour or provide antireflection have been found in both living and extinct animals in a diversity of forms, including mirror-reflective and diffractive devices. An overview of this diversity is presented here, and behavioural and evolutionary implications are introduced.

https://iopscience.iop.org/article/10.1088/1464-4258/2/6/201/pdf

515 million years of structural colour

Progress in the chemistry of melanins and related metabolites

Reexamination of the structure of eumelanin

on his own subject; in this book the reader will not be disappointed. Moreover, the translation from the original French, with the inclusion of some new material, suffers from few of the defects so frequently seen, for it reads fluently and spontaneously as if it were the original text. The first chapter deals with the nature of light and its relation to other forms of radiant energy: a succinct and interesting review, followed by a full description of different types of illuminants including the various types of artificial lighting and natural lighting from the sun. This is followed by a description of the physiology of vision and the functioning of the eye shown by experiments carried out on the human eye by physical methods. This part comprises a full discussion of such problems as photometry, the illumination of the retina, luminance efficiency and the duality of the retina, colorimetry and the trivariance of the retina, colour vision and its anomalies, and the various thresholds, time effects, and the spatial interactions affecting vision. The second section of the book is more physiological and speculative. It is introduced by a description of the relevant anatomy of the eye, the photochemistry and electrophysiology of vision, the various theories of colour vision, and a physiological interpretation of the visual thresholds. The book is easy and good to read and gives a fair and critical exposition of its subject. It should be useful not only to the ophthalmologist but also to the physiologist and physicist.

https://bjo.bmj.com/content/bjophthalmol/53/1/66.1.full.pdf

Light, Colour and Vision

The reflecting material of the tapetum lucidum of the sea catfish (Arius felis) was chromatographed on Sephadex LH-20 in methanol–dimethyl sulphoxide–formic acid. Two components were present: one, showing an absorption maximum at 330nm, was tapetal pigment; the other, at 257nm, was an associated nucleoside. The tapetal pigment was extracted in methanol–HCl and isolated by adsorption chromatography on Sephadex LH-20. It yielded a methoxy methyl ester on treatment with diazomethane, and permanganate oxidation gave pyrrole-2,3,5-tricarboxylic acid. From the information provided by u.v. and i.r. spectra of the pigment and its methoxy methyl ester, from elemental analyses and from the oxidation products, we suggest that the tapetal pigment is derived from oxidative coupling of 5,6-dihydroxyindole-2-carboxylic acid. A molecular-weight determination and chromatography of the methoxy methyl ester indicate that the pigment is a mixture of oligomers, among which the tetramers probably predominate. We consider that the monomers are joined mainly by C-C linkages at positions 4 and 7. A synthetic pigment having spectral properties nearly identical with those of the natural pigment was prepared by enzymic oxidation of 5,6-dihydroxyindole-2-carboxylic acid with mushroom tyrosinase. The identity of the tapetal pigment with the synthetic pigment was further confirmed by comparing u.v. and i.r. spectra of their methoxy methyl esters. Formation of the tapetal pigment from tyrosine and relationships of the tapetal pigment to melanin are discussed.

/pdf/isolation-of-oligomers-of-5-6-dihydroxyindole-2-carboxylic-4dfdc4lejs.pdf

Isolation of oligomers of 5,6-dihydroxyindole-2-carboxylic acid from the eye of the catfish

Effects of water-soluble components of petroleum oils and aromatic hydrocarbons on Barnacle larvae

Ocular reflecting pigments of some malacostraca

Eyes of four species of gars were studied, namely, alligator (Lepisosteus spatula Lacepede), spotted (L. oculatus (Winchell)), shortnose (L. platostomus Rafinesque), and longnqse (L. osseus (L.)). The retina is duplex, a yellow tapetum lucidum is present, rods and retinal pigment move, and the tapetum is uncovered in dim light. The visual pigment is a porphyropsin, λmax 523, and the optical density of the pigment in the retina is 0.22. Transmission through the retina is low at short wavelengths and rises steeply above 460 nm. Reflectance from the tapetum is diminished in the blue, and rises progressively at longer wavelengths to reach a maximum (70%) at about 650 nm. Underwater illumination was measured in waters where gars occur. In lake waters maximal transmissivity occurred at 375 nm and the transmission per meter ranged from 76 to 62%. In rivers and bays, transmission was maximal at long wavelengths, ≥600 nm, and the transmission per meter ranged from 37% to 0.001%; these waters sometimes were stained...

J. A. Colin Nicol

Papers

Isolation of oligomers of 5,6-dihydroxyindole-2-carboxylic acid from the eye of the catfish

Effects of water-soluble components of petroleum oils and aromatic hydrocarbons on Barnacle larvae

Ocular reflecting pigments of some malacostraca

The tapetum lucidum of gars (Lepisosteidae) and its role as a reflector.

he tapetum luciaum or gars (Lepisostei d its role as a reflector idae) an