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The structures of the eyes of two Staphylinid beetles, one large ( Creophilus erythrocephalus-18 mm in length) and one small ( Sartallus signatus-3 mm in length), were compared. 1. The gross structure of the two eyes is the same: Considerable differences exist in size, shape and arrangement of rhabdom, retinula cells and their axons. The smaller size of the eye of Sartallus is caused by reduction of number of facets rather than cell size, and, in fact, retinula cells and rhabdom have been found to be larger in the smaller beetle. 2. Structural changes during dark-light-adaptation affect crystalline cone, position of screening pigment and size of intercellular spaces between the retinula cells. In the dark-adapted state the cone retracts a little and the crystalline tract becomes wider. A thickening of cone cell extensions occurs just above the rhabdom. Screening pigment migrates to a more distal position and intercellular spaces between the retinula cells considerably increase in size as compared with the light-adapted eye. 3. Both eyes are rich in irregularities. An attempt to classify anomalies of compound eyes has been made. The number of cone cells and principal pigment cells varied, in some cases, from 1-5 and 0-3 respectively. Basal retinula cells did not always contribute to the rhabdom. 4. Interferometrical observations reveal the extreme optical homogeneity of the entire corneal cuticle of the eyes of both species. No layers of different refractive index or optical separation of adjacent ommatidia can be found. The refractive index of the cornea of Creophilus is 1.469; that of Sartallus is 1.488. 5. Functional consequences of the changes which occur during dark-light-adaptation are discussed. Exposure to intense light appears to cause a rapid aging of retinula cells, which is indicated by an increase of onion- and multivesicular bodies. [ABSTRACT FROM AUTHOR]

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Copyright of Diabetologia is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)