Hata started out by doing long tests with 606 on spirochetes not so pale or so dangerous. There was that spirochete fatal to chickens.... The results? “Un-heard ... of! In-cred-i-ble!” shouted Paul Ehrlich. Chickens and roosters whose blood swarmed with that microbe received their shot of 606. Next day the chickens were clucking and roosters strutting--it was superb. But that disease of the loathsome name? On the 31st of August, 1909, Paul Ehrlich and Hata stood before a cage in which sat an excellent buck rabbit. Flourishing in every way was this rabbit, excepting for the tender skin of his scrotum, which was disfigured with two terrible ulcers, each bigger than a twenty-five-cent piece. These sores were caused by the gnawing of the pale spirochete of the disease that is the reward of sin. They had been put under the skin of that rabbit by S. Hata a month before. Under the microscope--it was a special one built for spying just such a thin rogue as that pale microbe--under this lens Hata put a wee drop of the fluid from these ugly sores. Against the blackness of the dark field of this special microscope, gleaming in a powerful beam of light that hit them sidewise, shooting backwards and forwards like ten thousand silver drills and augers, played myriads of these pale spirochetes. It was a pretty picture, to hold you there for hours, but it was sinister--for what living things can bring worse plague and sorrow to men? Hata leaned aside. Paul Ehrlich looked down the shiny tube. Then he looked at Hata, and then at the rabbit. “Make the injection,” said Paul Ehrlich. And into the ear-vein of that rabbit went the clear yellow fluid of the solution of 606, for the first time to do battle with the disease of the loathsome name. Next day there was not one of those spiral devils to be found in the scrotum of that rabbit. His ulcers? They were drying already! Good clean scabs were forming on them. In less than a month there was nothing to be seen but tiny scabs--it was like a cure of Bible times--no less! And a little while after that Paul Ehrlich could write: “It is evident from these experiments that, if a large enough dose is given, the spirochetes can be destroyed _absolutely and immediately with a single injection_!”