EGGS AND EGG-COLLECTING. 9 



Moulting has been rendered subject to the law of 

 preservation in a remarkable degree, for where birds 

 are open to periodical changes of surrounding con- 

 ditions which materially affect their existence, they are 

 provided with an extra moult. For example, the Ptar- 

 migan's plumage is pure white for winter snow, and 

 brown for summer heather. 



The stoat's fur undergoes a similar change of colour ; 

 and more marvellous still, to pursue the preservation argu- 

 ment into the water world, take a common trout, and chase 

 him up and down a shallow pool until he has become 

 thoroughly scared, and it will be found that wherever he 

 rests for a few seconds his colour will change in obedience 

 to that of the bed of the stream directly beneath him ; so 

 much so that I have known one half of a trout very dark 

 and the other half very light coloured, correspondingly with 

 objects beneath and around him. 



Again, the same high authority points out that "the 

 feathers of young birds are in male and female similar to 

 the female parent when she is of a dull colour, but like the 

 male when he is dull and the female bright ; also, when both 

 parents are of a conspicuously bright colour the young take 

 a dull colour of their own " — for example, Robins. He infers 

 that these colours represent those of far distant progenitors ; 

 but as safety lies in these modified tints, and preservation 

 being Nature's chief problem, it is more reasonable to suppose 

 that Nature lends this means of protection whilst the bird 

 is in its most helpless condition, for an evolution that tends 

 to increase dangerously conspicuous colours would only 

 seem to invite extinction. 



In another place he says " it deserves especial attention 

 that brilliant colours have been transferred much more 



