RECENT RESEARCH UPON SALMON 235 
inorganic substance known as guanin. The salmon has not 
been many days in the fresh water before this brilliancy 
becomes duller, until, after a sojourn of some weeks, the males 
become ruddy brown and copper-coloured, the females sooty 
grey and purplish. Fishermen usually regard this as the result 
of the oxidising properties of fresh water, and indeed it is very 
similar in effect to the tarnishing of silver. But this explanation 
fails to account for the phenomenon exhibited after spawning. 
Kelts rapidly use the dark tones assumed by gravid fish, and, 
before they reach the sea again, become as white and silvery as 
they were when they left it. It is probable that these changes 
in skin colour are independent of external agents, and arise 
from alterations in the circulatory system. In the higher 
vertebrates, the skin colour or complexion is intimately 
connected with the circulation; so, in the salmon, it is 
probable that when the blood stream is diverted from the 
stomach to the growing ovaries, not only does the stomach 
become functionless, but the effect is immediately seen upon 
the skin. After the milt or ova are deposited, the blood 
reverts to its normal course, the stomach begins to resume its 
normal condition, and the skin recovers its brilliancy. That, 
very roughly and briefly stated, is the conclusion to which 
research has tended, although the reader is entitled to be 
spared the physiological details upon which it rests, and also 
the evidence for the transference of ruddy pigment in the 
muscle of fresh-run salmon to the skin in the males and to the 
ovaries in the females. 
Then arises the question—what is a “ well-mended kelt,” 
so well known to anglers; a kelt, that is, which has 
recovered not only its lustre, but, apparently, regained some 
muscle? The process of “ mending’”’ has been well described 
by Professor Miescher Ruesch :— 
How altogether different is the picture if we have the opportunity to 
see the creature ten days, or, better, two weeks after spawning. The skin 
is again bluish, shining and clear; the ulcers cicatrised and healing, the 
