444 PACKARD— ORIGIN OF MARKINGS OF ORGANISMS. [Dec. 2, 



obliterating patterns. *' The act of flight tends to obliterate patterns, 

 by the too quick substitution of one color for another before the 

 eye. A black and white butterfly, therefore, tends to look simply 

 gray in swift flight." 



20. Experiments on the Obliteration of Bars and Spots with 

 Bradley's Color Wheel. 



The following experiments on the artificial blending and oblitera- 

 tion of stripes and spots, by means of a revolving disk covered with 

 parti-colored stripes or spots, throw, it seems to me, much light on 

 this subject and satisfactorily proves that the stripes, bars and spots, 

 contrasting with the ground colors of moths, butterflies, fishes, rep- 

 tiles, birds and mammals thus marked, must necessarily blend so as 

 to render the outline of the animal indistinct when it is in rapid 

 motion. 



I covered a six-inch black disk with squares of white paper about 

 a quarter of an inch wide, in imitation of the squarish white spots 

 on a loon's back. Moving the disk slowly there resulted three quite 

 distinct black rings about a quarter of an inch wide, separated by 

 white rings. When the wheel was revolved at full speed the black 

 ground color and white spots all blended into whitish pearl-gray, 

 of the general color of the under side of the loon's body. The 

 white spots certainly all produced a decidedly blurred, indistinct 

 whitish pearl-gray tone. It is thus probable that the loon's back 

 during rapid flight harmonizes with the neutral gray of the sky, 

 especially in cloudy weather, and tends to either obscure it or 

 render it more or less invisible. 



On a white disk was then pasted a series of wide dark brown 

 stripes, in imitation of the stripes on a zebra. On rapidly revolving 

 the wheel the stripes and ground color blended into a grayish-white 

 or neutral tint. On a six-inch black disk were pasted three sinuous 

 white bands from a quarter to half an inch in width, one white band 

 on one side one inch long and that on the opposite side five inches 

 long. When the disk was slowly revolved the black and white stripes 

 blended, but there were visible two darker rings ; but when the wheel 

 was revolved more rapidly all perfectly blended into a whitish-gray 

 hue like the color of the sky. This shows that the stripes of a zebra 

 when in rapid motion would be blended, and its outlines rendered 

 more or less indistinct, in accordance with the statements of differ- 

 ent hunters and naturalists. 



