SWANS 



POLISH SWANS. 



There is no doubt that the so-called Polish swans are 

 sometimes produced from birds that are to all appearance 

 the common mute swan (Cygnus olor). Many years ago, 

 when at Cambridge, Professor Newton called my attention 

 to a pair of common swans that had bred, and the young 

 birds were white when hatched, and continued to exhibit 

 all the characteristics of Polish swans. This leads me to 

 consider the subject of albinos, for it appears to me that 

 we have several varieties of albino birds and other animals ; 

 in the first place, the pure albino may be described as 

 purely white with pink eyes, having no colouring pigment 

 in its system. Now I find a great variety of these con- 

 ditions. The so-called Himalayan rabbits have perfectly 

 white bodies, but black legs, ears, nose, and tail ; at the 

 same time, they have pink eyes. I also find perfectly 

 white guinea-pigs with dark eyes. Among birds I find 

 purely white jackdaws, blackbirds, Java sparrows, and 

 other white finches with dark eyes. All these varieties I 

 regard as semi-albinos. I have thus arrived at the con- 

 clusion that the so-called ' Polish ' swans belong to this 

 group, and are semi-albinos, because they have the black 

 marking round the base of the bill and the dark eyes of 

 the common swan. 



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