Bluishness

[…] the blinds and curtains made it almost dark. Still from the pale bluishness which filtered in one could see that it was very early.

Should a stranger suppose that they were white, he would soon be told that they were halfcaste. Should one doubt it, as passing strangers sometimes did, the children would be seized if unprotected and have the whites of their eyes and bases of their finger-nails searched for that bluishness which is supposed to be the evidence of black blood.