Meanwhile he was scheming and groping about and having dreams about other things that might cause the arteries to harden, and suddenly he invented another cause--surely no one can say he discovered it!--“auto-intoxication, poisoning from the wild, putrefying bacilli in our large intestines--that is surely a cause of the hardening of the arteries, that is what helps us to grow old too soon!” he cried. He devised chemical tests--what awful ones they were--that would show whether the body was being poisoned from the intestine. “We would live much longer,” he said, “if we had no large intestine, indeed, two people are on record, who had their large intestine cut out, and live perfectly well without it.” Strange to say, he did not advocate cutting the bowels out of every one, but he set about thinking up ways of making things there uncomfortable for the “wild bacilli.” His theory was a strange one, and caused laughter and jeers and he began to get into trouble again. People wrote in, reminding him that elephants had enormous large intestines but lived to be a hundred in spite of them; that the human race, in spite of its large intestine, was one of the longest-lived species on earth. He engaged in vast obscene arguments about why evolution has allowed animals to keep a large intestine--then suddenly he hit on his great remedy for auto-intoxication. There were villages in Bulgaria where people were alleged to live to be more than a hundred. Metchnikoff didn’t go down there to see--he believed it. These ancient people lived principally upon sour milk, so went the story. “Ah! there’s the explanation,” he muttered. He put the youngsters in his laboratory to studying the microbe that made milk sour--and in a little while the notorious Bulgarian bacillus made its bow in the rank of patent medicines. “This germ,” explained Metchnikoff, “by making the acid of sour milk, will chase the wild poisonous bacilli out of the intestine.” He began drinking huge draughts of sour milk himself, and later, for years, he fed himself cultivations of the Bulgarian bacillus. He wrote large books about his new theory and a serious English journal acclaimed them to be the most important scientific treatises since Darwin’s “Origin of Species.” The Bulgarian bacillus became a rage, companies were formed, and their directors grew rich off selling these silly bacilli. Metchnikoff let them use his name (though Olga insists he never made a franc from that) for the label.