430 FRANCIS B. SUMNER 



was in contrast to the behavior of other fishes in the room, and in 

 noteworthy contrast to its own previous and subsequent behavior. 

 Upon being transferred later to the 1 cm. squares, it became tran- 

 quil at once. Equally interesting was the condition of the chro- 

 matophores while the fish was kept on these largest squares. 

 Although this was the same specimen which had shown the coarsely 

 blotched appearance upon the 2 cm. squares, the skin now took 

 on a nearly homogeneous appearance (fig. Ig). This was nearly 

 or quite of the same as the appearance of this and some other 

 specimens while swimming. Specimen no. 4 did not exhibit so 

 complete an effacement of its previous pattern when transferred 

 to these largest squares, but the contrasts were greatly reduced. 

 (Fig. 4f, not fig. 4^, which represents the condition at the com- 

 mencement of active movement) . The results from the tests with 

 this pattern are perhaps such as might have been expected on the 

 assumption that the areas were too large to admit of their under- 

 going a synthesis in the creature's brain. The animal's atten- 

 tion has perhaps vacillated between the light and the dark areas, 

 with a resulting indecision as to what to do.^- 



14. White (or black) circular spots, upon a background of the 

 opposite shade. The spots were of such a diameter, and spaced in 

 such a manner, that their aggregate area was about one fourth 

 that of the background. These patterns were used to determine 

 to what extent differences in the proportional amounts of black 

 and white in the underlying surface would lead to corresponding 

 differences in the skin of the fish. Specimens 1 and 4 were again 

 used for this purpose, and figs. Ij, 11, M, and 4e give a decisive 

 answer to this question. The appearance of no. 4 upon the 

 darker of these two patterns (fig. 4e) was, indeed, one of the most 

 picturesque results which I obtained in the course of my experi- 

 ments. Despite the difference between the two in the form of the 

 spots, and the fact that the intra-annular areas were not of as 

 pure a white as on some other occasions, the animal merged al- 

 most insensibly into its background, and was scarcely visible 



'2 The reader is at liberty to substitute less 'anthropomorphic' language, if 

 his sensibilities are jarred by these words. 



