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COLOUR CHANGES IN BIRDS' FEATHERS. 

 I'',\ Q-. P. ITeumann. 



As a boy I wondered why European linnets should lose the carmine breast 

 leathers in captivity, and since then I have kept in my aviaries many species 

 of birds, which during the first moult in captivity lost the scarlet in their plum- 

 age, or the colour in which scarlet was a component part, like orange, either 

 altogether, or at least changed it ranging down from yellow to a dirty pink or 

 creamy white. For instance, the Sepoy Finch from India, a lovely scarlet bird, 

 became yellow; the Scarlet Breasted Robin of Australia a poor pink, or a dirty 

 white. What is the cause of these colour changes? 



When I commenced my investigations into this interesting subject I sup- 

 posed that the whole of the colouring matter as we see it in birds' feathers, was 

 caused by the minute structure of the feathers. That is to say, I took it that 

 colour as we see it was produced by interference of the light waves and that 

 through unnatural feeding the minute parts of the barbieels would in captivity 

 during the moult become stunted or malformed. If then there was any difference 

 in the minute structure in the feathers and their positions before or after the 

 moult, the quality of the light reflected therefrom would be different and in this 

 way would create a change in colour in various degrees as the malformation 

 might be slight or severe. 



Chemical experiments conducted later have shown me the imperfection of 

 the theory I had embraced, and I had to acknowledge the existence of pigment 

 in feathers. Yet even the chemical colours must be subject to microscopical 

 differences of structure of the infinitesimal parts of which pigment itself con- 

 sists. If this be admitted then we might say that all ' colour is produced by 

 structure. 



Each feather as we know consists of barrel, shaft and aftershaft, and during 

 the growing period of the feather the aftershaft is the medium through which 

 the feather is fed. 



The principal seat of the pigment which produces the chemical colours in 

 the feathers seems to be in the capilliaries of the mucous membrane which lies 

 below the surface skin of the horny parts of the feather. When the feather has 

 attained maturity the blood and the opaque substanee in the aftershaft recede 

 or dry up and now the feather is dead — at all events not subject any more to 

 matter changes in the body. 



The pigment is first transmitted by the parents to the offspring, that is to 

 say by way of inheritance. The formation of the pigment, however, apart from 



