The first thing the Commission did was to fail to find any microbe whatever in the first eighteen cases of yellow fever that they probed into. There were many severe cases in those eighteen; there were four of those eighteen cases who died; there was not one of those eighteen cases that they didn’t claw through from stem to gudgeon, so to speak, drawing blood, making cultures, cutting up the dead ones, making endless careful cultures--and not one bacillus did they find. All the time--it was July and the very worst time for yellow fever--the soldiers were coming out of the hospital of Las Animas feet first. The Commission failed absolutely to find any cause, but that failure put them on the right track. That is one of the humors of microbe hunting--the way men make their finds! Theobald Smith found out about those ticks because he had faith in certain farmers; Ronald Ross found out the doings of those gray mosquitoes because Patrick Manson told him to; Grassi discovered the zanzarone carrying malaria because he was patriotic. And now Walter Reed had failed in the very first part--and anybody would say it was the most important part--of his work. What to do? There was nothing to do. And so Reed had time to hear the voice of that Theorizing Old Fool, Dr. Carlos Finlay, of Habana, shouting: “Yellow fever is caused by _a mosquito_!” The Commission went to call on Dr. Finlay, and that old gentleman--everybody had laughed at him, nobody had listened to him--was very glad to explain his fool theory to the Commission. He told them the ingenious but vague reasons why he thought it was mosquitoes carried yellow fever; he showed them records of those awful experiments, which would convince nobody; he gave them some little black eggs shaped like cigars and said: “Those are the eggs of the criminal!” And Walter Reed took those eggs, and gave them to Lazear, who had been in Italy and knew a thing or two about mosquitoes, and Lazear put the eggs into a warm place to hatch into wigglers, which presently wiggled themselves into extremely pretty mosquitoes, with silver markings on their backs--markings that looked like a lyre. Now Walter Reed had failed, but you have to give him credit for being a sharp-eyed man with plenty of common sense--and then too, as you will see, he was extraordinarily lucky. While he was failing to find bacilli, even in the dreadful cases, with bloodshot eyes and chests yellow as gold, with hiccoughs and with those prophetic retchings--while he was failing, Walter Reed noticed that the nurses who handled those cases, were soiled by those cases, never got yellow fever! They were non-immunes too, those nurses, but they didn’t get yellow fever. “If this disease were caused by bacillus, like cholera, or plague, some of those nurses certainly should get it,” argued Walter Reed to his Commission.