NOTE ON INTERNAL ALBINISM. 
By KARL PEARSON, F.R.S. 
The authors of the previous paper having referred to my use of the term 
internal albinism, it may not, perhaps, be out of place to say a few words on that 
subject. This is not done because any conclusions on this point have been so 
far worked out, but because the investigations upon which they must turn will 
perforce have to be made by others with not only the adequate training but the 
requisite material, — a material which is rarely available, and which without such 
suggestions, as I wish to bring forward, may possibly not be used to the maximum 
advantage when it does occur. This must be my excuse for putting forward some 
rather vague suggestions instead of demonstrated facts ; I hope that, among many 
other questions of interest, they may be partially answered when the opportunity 
arises. 
With the exception of an occasional eye or part of an eye no post-mortem 
account of a human albino has appeared in print as far as I am aware between 
1783 and 1910. Buzzi in 1783 had not the histological knowledge which would 
have enabled him to throw light on our modern problems. In Adler and M'^Intosh's 
case the age of the child was too slight for the case to give information as to the 
internal pigment of a fully developed human albino. In the case of the post- 
mortem examination recorded below the answers to several of my problems could 
have been given, but the problems were not in the mind of the medical man who 
made the examination. It is because such examinations must be very infrequent 
that I venture to throw out my queries and suggestions in the hope that they may 
reach physiologists and pathologists ; and that although originating in a layman 
they may consider them worthy of investigation. 
In the case of albinism in man there is no doubt of the largely relative 
character of the absence of superficial pigment*. Almost every grade of albinism, 
whether we consider the eyes, hair, or skin, occurs. But there is something more 
than graduated intensity of pigmentation ; there may be local complete absences 
of pigment ; besides incomplete albinism, we have partial albinism and this in 
a great variety of stages. Intensity and distribution of the superficial pigment 
* The terms " superficial pigment " and " external albinism " are used to cover the visible pigment, 
or pigment exposed to the action of light. They include the retinal pigment although its morphological 
origin brings it into closer relation with the internal pigment of the brain centres. 
