Karl Pearson 
353 
contact with them every day in a large but poor practice. He has, I feel sure, no 
bias to any theory of heredity, and I think my questions first put the modern 
theory before him. The main point is that the segregation in the second genera- 
tion to pure white or black skins does not occur. One quotation more from his 
letters, which had reference to the question of whether the lighter shades of the 
mixed race might have a dark skin as a latent quality. 
" Now I think the question you wanted an answer to is this : When the mixed breed 
approaches the European side, are there reversions to a definitely negroid type ? You reserved 
your opinion when I saw you in the summer, until I had formulated my experience. That 
experience is that such reversions are comparatively rare, sufiiciently rare to be practically 
disregarded in a court of law in the decision of bastardy paternity cases. I cannot give you 
definite statistics, the subject, as you may well imagine in a mixed race community like this, 
bristles with delicate social difficulties. After many years of medical practice here among all 
classes and colours I feel sure that I am justified in saying that the reversions to the negroid 
type are distinctli/ uncommon. Of course in families of the mixed breed you will often see a 
difference in colour pure and simple ; this is not at all uncommon, and I would make a marked 
distinction between this phenomenon and the phenomenon of a throwback to the negro. You 
will not infrequently see the same thing in European families, and if you are going to consider it 
in the case of Englishman x Negro, you must also consider how it would apply in the case of 
Englishmen x Englishwomen." 
I take it that my correspondent is here referring to the continuous variability 
within the family — demonstrably inheritable, — which some disciples of Mendel 
term " fluctuating " variability and believe to have no importance for the theory 
of heredity. 
" ' Sports ' or ' throwbacks ' do occur, but are really rare ; the milder form, i.e. the form which 
is barely evident in tint is not uncommon, but only a practised or accurately observing eye 
would detect it. ' Sports ' to the pure white or the pure negro are practically unknown ; in all 
my life I have not heard of a single one." 
In view of the opinions I have cited above, I think, the suggestion that skin 
colour ' mendelises ' should not be vaguely made until some very definite evidence 
in its favour is forthcoming. I should welcome any views on the above four 
questions from those having life-long experience of mixed races, or having from 
mission or medical work special opportunities of studying the offspring of mixed 
races. Actual data as to skin tints taken on Broca's or von Luschan's scales 
would be very valuable, and any photographs of individuals of mixed race, taken 
when possible alongside individuals of the two pure races, will receive a ready 
publication in this journal. 
Biometrika vi 
45 
