1868.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 415 



Turkey Buzzard (Cathartes aura). 



March 11, 1882, in Henrico County, Va., saw a turkey buzzard with 

 several white primaries in each wing. 



The subject of albinism among birds has always been a matter of in- 

 terest to me, and I have carefully read whatever I have had access to 

 upon this subject, as well as articles upon the coloration of the feathers 

 and changes of coloration, and albinism in general ; but I must confess 

 that such information as I could obtain has been meager and unsatis- 

 factory in the extreme, most authors merely referring to albinism as a 

 fact, and giving no further explanation than that they were ignorant of 

 its causes. Darwin refers to it several times, but discusses it more as 

 a matter of heredity. It is easy to see the difficulty of studying this 

 phenomenon among birds, for, first, its instances are rare ; second, when 

 they are met with the bird is immediately destroyed, if possible, and its 

 skin secured ; third, the absence of means for ascertaining the changes (if 

 any) that the bird has goue through from the moment it was hatched 

 until it was secured; and fourth, it is hardly probable that a private 

 collector, even during a life-time, should meet with a sufficient num- 

 ber of examples to enable him to draw up with any confidence general- 

 izations from his observations which would include all cases. 



We are therefore driven to consider the cases of albinism that we 

 can observe during their existence, and then by analogy apply our de- 

 duction to birds. This is unsatisfactory and uncertain. 



There is the human albino, too well known to need description ; then, 

 among other mammals, instances of hereditary albinism; as, for ex- 

 ample, English rabbits, white rats and mice, etc. Among domesticated 

 birds it is rarer; a white plumage made hereditary by interbreeding, 

 as (to take the more recent instances ) in white turkeys, guinea hens, 

 etc., not constituting a perfect albinism as we understand it. Consider- 

 ing these cases, we find that for the mammals : 



(1) Albinism exists as a freak — has its inception in embryo, exists from 

 the moment of birth, affects, as a rule, the entire body and lasts through 

 life. 



(2) The negative statement of the above : It is not the result of disease ; 

 the whitening of the skin and hair produced by leprosy and kindred 

 diseases not constituting true albinism. 



(3) It arises, in the human being, -'from the absence of the minute 

 particles of coloring matter which occur in the lowest and last deposited 

 layer of the epidermis." 



Now, if we endeavor to apply these conclusions to birds, we immedi- 

 ately meet with difficulties; for instance: 



(1) "Albinism exists as a freak, has its inception in embryo, exists 

 from the moment of birth." (Since the receipt of your favor of the 12th 

 ultimo,* stating that there are in the National Museum several speci- 

 mens showing that some albinos are hatched pure white, we must with- 

 out hesitation admit that much; but does it follow that all albinos are 



* Reference is here made to a letter from the Curator of the Department of Birds. 



