Dr John Davy on the Colour of the Salmon. 249 
muscle of the salmon is rendered paler by the action of 
a strong solution of ammonia—the aqua ammonie—the 
solution itself remaining colourless. By strong nitric acid 
it is rendered yellow; by strong sulphuric, brown; by a 
solution of potash—the liquor potassee—brown ; by strong 
muriatic acid a slight change of colour is produced ; whilst 
rendered paler, it acquires a brownish tint. Both the strong 
acids, the nitric and the sulphuric, it may be remarked, and 
also the solution of potash, have a disorganising, decomposing 
effect, to which the change of colour they occasion may 
principally be attributed. Alcohol and ether render the 
muscle of a lighter hue, but do not deprive it entirely of 
colour. Both become very slightly coloured, and on cooling 
and evaporation deposit and leave a colourless liquid oil. 
Granting that the colour belongs to the muscular fibre,— 
2.e., that the colouring matter is seated in the muscle irre- 
spectively of fat,—the further conclusion I would submit 
is, that it is of an organised kind. It may be a peculiar 
colouring matter nowise essential to the muscle (some of 
the muscles, as I have pointed out, being without this 
colour), and analogous to those colouring matters which 
exist in plants, especially their leaves and flowers, and in the 
tegumentary parts of mammalia, birds, and fishes,—such as 
the hair of the first, the feather of the second, and the 
epidermis of the ‘ame 
Whether the peculiar colour or colouring matter owes its 
formation to some particular kind of food, or to a special 
secreting power, I am not aware of any well-marked facts 
to guide one to a conclusion. So far as probabilities are 
concerned, I am rather inclined to the belief that it depends 
partly on the one partly on the other. 
Some Observations on the Eggs of Birds. By Joun Davy, 
M.D, FT RS., duond..& Edin. &e:* 
Although few objects have received more attention from 
the physiologist and chemist than the egg of the common 
* Read at the Meeting of the British Association for the Advancement of 
Science (Newcastle, 1863.) 
