The refractive significance of the nictitating membrane of the bird eye

Summary Previous authors have suggested that in certain aquatic birds a transparent nictitating membrane of high refractive index could compensate for the refractive loss of the cornea in water. Measurements of refractive indices, refractive state and curvature carried out on a number of aquatic birds indicate that the nictitating membrane does not have a refractive function; the refractive indices of the cornea and nictitating membrane are very similar (approximately 1.37), the nictitating membrane does not alter the refractive state of the eye, and its curvature, when it is in place in front of the globe, is virtually the same as that of the cornea.This research was supported by grants from the National Research Council of Canada and the Canadian National Sportsmen's Fund. The assistance of Mote Marine Laboratory, The Mount Desert Island Biological Laboratory, the Niska Wildlife Foundation and the Felicadades Wildlife Foundation is gratefully acknowledged. The herring gulls and black guillemots were provided by Dr. W.B. Kinter. In addition, the authors are grateful for the assistance provided by Drs. J.L. Lincer and D. Peakall and Mr. R. Orleib.     

Characterization of the mouse liver cell line FL83B

The previously reported mouse liver cell line FL83B has been characterized more completely with respect to its light and electron microscopic appearance, chromosomal composition, and ability to secrete various serum proteins. These cells bear many striking morphological similarities to parenchymal liver cells. Chromosomal analysis showed that the cells were transformed. The ability of these cells to grow in a completely chemically defined medium permitted the unequivocal demonstration of the synthesis of at least 12 mouse serum proteins including albumin and high density lipoprotein.