Washouts, most of these experiments; but one day, in the blood of a native cow from the Island of Kome, not hurting that cow at all, but ready to be sucked up by the tsetse for stabbing under the skin of the first man it meets, Bruce found the trypanosome of sleeping sickness. He sent out word, and presently a lot of bulls and cows were driven up the hill to Mpumu by order of Apolo Kagwa. Bruce, himself in the thick of it, directed dusty fly-bitings of these cattle--yes! there was no doubt the sleeping-sickness virus could live in them. Then there were scuffles in the hot pens with fresh-caught antelope; they were thrown, they were tied, Bruce held dying monkeys across their flanks, and let harmless tsetses, bred in the laboratory, feed on the monkey and then on the buck.... “The fly country around the Lake shore will have to be cleared of antelope, too, as well as men--before the Kivu become harmless,” Bruce said at last to Apolo. And now the sleeping death really disappeared from the shores of Lake Victoria Nyanza. VIII The ten thousand smaller microbe hunters who work at lesser jobs to-day, as well as the dozen towering ones whose adventures this book tells, all of them have to take some risk of death. But if the ten thousand smaller microbe hunters of to-day could by some chemistry be changed into death fighters like Bruce! There was something diabolical in the risks he took, and something yet more devilish in the way he could laugh--with a dry humor--and wish other microbe hunters might have died to prove some of his own theories. But he had a right to wish death for others---- “Can young tsetse flies, bred in the laboratory, inherit the sleeping-sickness trypanosome from their mothers?” Surely there was a chance of it (you remember that strange business of Theobald Smith’s mother-ticks bequeathing the Texas fever microbe to their children). But analogies are for philosophers and lawyers. “_Are_ artificially hatched young tsetses dangerous?” asks Bruce. “No!” he can answer. “For two members of the commission” [modestly he does not say which two members] “allowed hundreds of tsetse flies, bred in the laboratory, to bite them. And the result was negative.” But no man knew what the result would be--before he tried. And the deaths from sleeping sickness (according to the best figures) are one hundred out of one hundred....