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Differences in the staining properties of yolk deposited during night and day were used to estimate the time required to deposit yolk within the ovarian follicle. Whole eggs were frozen to -10° C. to alter the lipoproteins, the shell was removed, and contents fixed in 4% formalin for 18 hours at 60-70° C. The yolk was cut in half, and one half was put into 6% potassium dichromate for 18 hours at 60-70° C. Slices revealed alternating light and dark grey-green or brown rings. The center (latebra) was always light. From timed dye-feeding experiments it was found that lighter staining rings were deposited at night. Chicken eggs had 7-11 light rings; coturnix quail 4-6; turkeys 10-12; and cackling geese 12. All eggs from a variety of bird species showed ring structures.Staining formalin-fixed slices with acidified ferrocyanide yielded rings of Prussian blue, a test for forms of iron.Variation in the nutrition of the reproducing female, or the effects of acute contacts with environmental contaminants can be localized in discrete rings of yolks without experimental intervention during yolk deposition.

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. University of California Press and CooperOrnithological Society are collaborating with JSTOR to digitize, preserve and extend access to The Condor.Abstract. Pollens fed to adult and nestling hummingbirds were largely unaffected by passage through the digestive tracts. Adult lorikeets and Cockatiels (Nymphicus hollandicus) responded similarly, but their nestlings were somewhat more able to digest pollens. Eucalyptus, Zauschneria, and Callistemon pollens were fed to nestling and adult Anna's Hum- mingbirds (Calypte anna) and adult Costa's Hummingbirds (C. costae). Eucalyptus and Prunus pollens were fed to adult Rainbow Lorikeets (Trichoglossus haematodus haematodus), adult and nestling Moluccan Lorikeets (T. h. moluccanus), and adult and nestlingCockatiels. Empty grains were considered to be digested. Hummingbirds digested less than 7% of all the pollens fed. Adult lorikeets digested less than 7% of the Eucalyptus pollen, and nestlings digested 24%. Adult Cockatiels digested 17% and nestlings 38% of the Eucalyptus pollen. Neither psittacine digested more than 4% of the Prunus pollen. It was concluded that the pollens did not furnish a significant source of energy or protein to the birds.