Life-history of Salmon. 1 15 



unaccounted for may possibly be derived from the blood 

 (|..lo8). 



Tlie pigment of tlie salmon was investigated by Miss M. I. 

 Newbigin. Tlie nuptial colour-changes of the fish are well 

 known. " \^'hen tlie fish comes from the sea the skin is of a 

 clear bright silvery hue, while the flesh has the familiar 

 strong ])ink colour. The small ovaries are of a yellow-brown 

 colour. As the reproductive organs develop during the 

 passage uj) the river certain definite colour-changes occur. 

 The skin loses its bright silvery colour, and, more especially 

 in the male, acquires a ruddy brown hue. At the same time 

 the flesh becomes paler and paler, and in the female the 

 r;ipidly growing ovaries acquire a fine orange-red colour. 

 The testes in the male remain a creamy white. 



" After spawning the skin tends in both sexes to lose its 

 ruddy colour and to regain the bright silvery tint ; the flesh, 

 however, remains pale until the kelt has revisited the sea. 

 In other words, the salmon comes from the sea with a store 

 of pigment in the muscles During its sojourn in the river 

 this |)igment disappears fiom the muscles, is apparently in 

 the female for the most jiart transferred to the ovaries, and so 

 to the ova, and in both sexes is to a smaller extent deposited 

 in the skin, there to undergo further changes. The accumu- 

 lation of pigment in the muscle is associated with the presence 

 of a large amount of fat, and fat and pignie,nt disappear pari 

 passu " (p. 159). 



A similar colour-cliange is observable, although in a lesser 

 degree, in the Sea-Trout, and " even in certain varieties of 

 brown trout, e. g. the Loch Leven trout " ; and it is suggested 

 that in the case of certain red-fleshed fish of other families, 

 such as the Dawson Salmon of the Australians {Osteoqiossam 

 Leic/iardti^ mid the Australian mud-fish [Ceratodus Forsteri), 

 the pigment is also associated with the presence of fat in the 

 muscles. 



Miss Newbigin's chemical investigations disclosed the 

 presence, both in the flesh and in the mature ovaries, of two 

 pigments. Of these " one is pink and gives the blue lipo- 

 chrome reaction, while the other is yellow and does not give 

 this reaction" (p. IGI). The former " corresi)onds closely 

 to the lijjochrome pigment described in various animals, and 

 notably in Crustacea, as tetronerythrin or zoonerytluin (by 

 Moseley as crustaceorubrin) " (p. 161). The latter strongly 

 resembles a pigment which may be obtained from the bright 

 yellow fat of the cow. " It belongs to a group of pigments 

 which are apparently exceedingly widely distributed in the 

 animal kingdom, but which have been little investigated." 



