204 EARL W. BENJAMIN 



place by small circles of stock film made by cutting strips of film about 

 3 inches long and J inch wide and gluing the ends together. These film 

 circles are transparent, thus casting no shadow, and are therefore much 

 more suitable than if made of an opaque substance such as cardboard or 

 metal. When the twelve eggs that are to be reproduced on each 9x 11- 

 inch sheet are placed on the film, they are arranged evenly by means 

 of a separate frame shown in figure 9, which divides the 9x1 1-inch 

 space into twelve equal parts. This frame is removed before the repro- 

 duction is made. After the frame with the eggs on it is in place under 

 the light, the light is turned on for an exposure varying with its power 

 and its distance from the eggs. In this study, a 200-candle-power tungsten 

 light, with a special parallel-ray reflector, was used, about 9 feet distant 

 from the eggs, and an exposure of just one minute was required. A red 

 light was used when working with the sensitized paper. 



After the exposed sheet has been developed, the eggs appear as white 

 outlines on a black background (fig. 10). A key is arranged at the 

 time when the exposure is made, whereby the numbers of the eggs repro- 

 duced are known, so that certain eggs can be cut out of the plate at any 

 time, rearranged, and photographed. 



COLOR CHARACTER 



The method of making selections for the color character, and of recording 

 the colors for reference during succeeding generations of the birds,, was 

 a difficult one to develop. Various schemes were contemplated and 

 many of these were tried. Schemes of using color tops or wheels, various 

 types of colorimeters, colored photography, and so forth, were considered, 

 but were discarded as being too slow, expensive, or inaccurate. It is very 

 difficult to match the color of an egg with that of any other surface. It was 

 decided that if a system of matching colors was to be followed, in order 

 to do the work rapidly the eggs must be matched to other eggs of standard 

 colors. s 



By a careful inspection of all eggs produced on the plant for several 

 cfcays, a graduated set of colors containing about fifty tones from chalk- 

 white to dark chocolate brown was obtained. The first seventeen of 

 these tones were the only ones used in the experiment. The contents of 

 these eggs were blown, and the shells were numbered consecutively and 



