APPENDIX C 



APPEARANCE OF SCALES AND SCALE 

 IMPRESSIONS (Appendix Plate 2) 



Impressions of scales in plastic offer a number 

 of advantages over the use of the scales them- 

 selves : 



1. The effect of dirt on the scales is mini- 

 mized — especially dirt on the unsculptured 

 surface. 



2. Duplicates can be made that are exact 

 copies of the scales. 



3. Impressions are easier to file and store 

 than scales mounted on glass slides and the 

 chance of breakage is reduced. 



The process of making plastic impressions was 

 described by Clutter and Whitesel (1956) and 

 by Koo (1962a). Impressions made with a cold 

 roller are not as satisfactory for salmon scales 

 as those made with the heat-press method. (In 

 1955, a series of salmon scale impressions made 

 with a jeweler's cold roller were compared with 

 those made with a heat press. The heat-press 

 impressions were greatly superior.) 



In appendix plate 2, scale A shows a section 

 of a sockeye salmon scale, and scale B shows an 

 impression of the same scale section. The photo- 

 graph of the impression shows slightly sharper 

 circuli with less fuzziness from dirt and foreign 

 material on the surface of the scale. Note that 

 the photograph of the impression was reversed 

 for comparison. 



APPENDIX D 



APPEARANCE OF NEGATIVE AND POSITIVE 

 PRINTS (Appendix Plate 3) 



When plastic impressions are made of the 

 scales, the ridges on the scale surface become 

 valleys in the impressions. Koo and Finn (1964) 

 found that the sharp troughs of the impressions 



and the ridges on the scales both appear as dark 

 rings when examined by transmitted light. When 

 either the scale or its impression is examined by 

 reflected light, these structures appear as light 

 rings. Because the circuli and adjoining inter- 

 spaces over much of the scale have about the 

 same width, and because some workers project 

 the scales by transmitted light and others use 

 dark-field techniques for direct microscopic ex- 

 amination, it makes little difference whether the 

 scale photograph is a positive or a negative print. 



In appendix plate 3 there is an example of 

 each type : Scale A is a positive print and scale 

 B a negative print of the same sockeye salmon 

 scale. 



The only real difference in the prints is in the 

 lx)sterior field where growth features are absent 

 anj'Avay. The density of the negative print more 

 nearly matches the unage seen under the projec- 

 tor, or through the microscope; negative prints, 

 therefore, were used in making this atlas. 



APPENDIX E 



TECHNIQUES OF PHOTOGRAPHING SCALES 



The scales were photographed by placing a 

 piece of high-contrast photographic enlarg- 

 ing paper uiuler the image from a scale projec- 

 tor set up in a darkroom. The image was first 

 carefully focused on a white paper in a print- 

 ing frame. Then, with only a darkroom safelight 

 on, a piece of the enlarging paper was substi- 

 tuted for the focusing paper, exposed, developed 

 in a high-contrast paper developer (minimum ex- 

 posure-maximum development), and fixed, 

 washed, and dried in the usual manner. 



Positive prints can be made by taking a pic- 

 ture of a scale with a microscope camera (a sin- 

 gle lens reflex camera on a microscope), or by 

 photographing the projected image with a cam- 

 era, then exposing and processing the same as 

 for any photogi'aph of a high-contrast subject. 



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U.S. FISH AND WILDLIFE SERVICE 



