From Peter Kemp's old TLS review of Jack London's letters, published in 1989:
For, as these letters frequently remind you, London identified fiercely with wild – and wolf-like – dogs. Singing himself "Wolf" to close friends, he built a home called Wolf House. Packing dogs into his fiction, he wrote four novels with hounds as heroes: The Call of the Wild, White Fang, Jerry of the Islands, and Michael, Brother of Jerry. London's fictional self-portrait, Martin Eden – at one time prone to "bark and whine" – is said to be a "bulldog." "Bastard," one of London's most ferocious short stories, unleashes his animosity in animal guise; illegitimate and rejected by his father, London depicts a dog vengefully killing the man who has called it "Bastard" and maltreated it. This kind of mutation isn't restricted to London's fiction. Correspondents are informed that he has "fought like a wolf" or decided "never again to howl on your doorstep." One idiom recurs with particularly curious frequency. Constantly announcing that he will "stand up on my two hind legs," he often exhorts others to do the same ("Now is the time for us to get right up in meeting on our hind legs"), as if the usual posture would be to be on all fours.