204 ON THE GROWTH OF THE SALMON. 
quence of having been a long time in the fresh water, 
had lost its brilliancy, and had acquired a very dark 
aspect. This fish one of my children requested to 
be permitted to carry; so, after having inserted the 
longer and smaller end of a slender forked twig 
under one of the gill-covers and drawn it through 
the mouth till the prize was retained in the angle 
formed by the fork, I gave it to the boy, who held 
it suspended with the tail downwards. After a lapse 
of several minutes, perceiving that the fish had lost 
all its blackness and had become perfectly bright, 
I directed the attention of my acquaintance to it, 
who could scarcely be persuaded that it was the 
same which he had captured a short time before, 
‘but supposed that I had secretly substituted an- 
other for it; however, the speedy resumption of 
its former dark complexion, which underwent no 
further mutation, completely convinced him of its 
identity. 
I shall not attempt to offer any explanation of 
the remarkable physiological phenomenon here re- 
corded; but, apart from the mysterious operation 
of psychological agency, its cause must undoubt- 
edly be sought for in the organization of the in- 
teguments. 
