THE COMMON TROUT. 209 



vermilion colour of the breast almost disappears 

 when placed in a white basin ; and the vivid 

 colours are as speedily recovered upon transferring 

 the animals to a black glazed earthen jar." * 



Mr. Shaw, also, without any knowledge of the 

 preceding experiments, had occasion to observe in 

 the course of his visits to his ponds, that when his 

 little fishes remained stationary in any part of 

 their enclosure, their hue always corresponded to 

 the colour of the bottom of that particular portion, 

 and that whenever they moved to another quarter, 

 where the ground was somewhat different in tint, 

 they underwent after a few minutes a correspond- 

 ing change. Wishing to determine this fact by 

 experiment, he procured two large earthen-ware 

 basins, one nearly white inside, the other nearly 

 black. " I then placed a living fish in each, while 

 at the same time I kept up a constant supply of 

 fresh water in them. The fishes were of their 

 natural colour when first placed in the basin ; but 

 they had not remained there more than four minutes 

 till each had gradually assumed a colour nearly ap- 

 proaching to that of the respective basins in which 

 they were placed. I next took the fish out of the 

 white basin and placed it in the black one, and the 

 fish which was in the black basin I placed in the 

 white, and the results were uniformly the same, 

 the fishes changing according to the colour of the 

 surface over which they are placed. I next placed 

 both fishes in one basin, when the contrast for a 



* Edinburgh New Philosophical Journal, vol. ix. p. 327. 



