1915: Generations of Russian tsars marrying German or Danish princesses had reduced the proportion of Russian blood in the imperial veins close to vanishing point. Maurice Paléologue, the French ambassador in Petrograd, calculated that for Nicholas II the figure was one part in 128, and for the tsarevitch, Alexis, one part in 256.
Source: Maurice Paléologue, An Ambassador’s Memoirs (1923), vol. I, pp. 324–5