James Wilson, The evolution of British cattle and the fashioning of breeds…
“ At the present day Aberdeen-Angus cattle are hornless, similar in weight to Shorthorns and Herefords, and black, with occasional white markings upon the back underline. In the stock-breeder's sense of the term the Aberdeen-Angus breed is pure; but the irregular occurrence of white on the underline suggests that from a more stringent point of view the purity is not absolute. For that matter, it is inconceivable that any set of animals of more than one cell—or even of one cell, perhaps—can ever be absolutely pure. ”
