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suspicion of malaria. He divided this flock up into three little flocks, he whispered Hindustani words of encouragement to them. Into each cage, with its sparrow, he let loose a flock of these mosquitoes.

Marvelous! Not a mosquito who sucked the blood of the healthy sparrow showed those dotted circles in her stomach. The insects who had bitten the mildly sick bird had a few. And Ronald Ross, peeping through his lens at the stomachs of the mosquitoes who had bitten the very sick sparrow—found their gullets fairly polka-dotted with the jet-black pigmented circles!

Day after day Ross killed and cut up one after another of the last set of mosquitoes. Day after day, he watched those circles swelling, growing—there was no doubt about it now; they began to look like warts sticking out of the wall of the stomach. And he watched weird things happening in those warts. Little bright colored grains multiplied in them, "like bullets in a bag." Were these young malaria microbes? Then where did they go from here? How did they get into new healthy birds? Did they, indeed, get from mosquitoes into other birds?

Excitedly Ronald Ross wrote to Patrick Manson: "Well, the theory is proved, the mosquito theory is a fact." Which of course it wasn't, but that was the way Ronald Ross encouraged himself. There was another regrettable interlude, in which the unseen hand of his incurable restless dissatisfaction took him by the throat, and dragged him away up north to Darjeeling, to the hills that make giant's steps up to the white Himalayas, but of this interlude we shall not speak, for it was lamentable, this restlessness of Ronald Ross, with the final simple experiment fairly yelling to be done. . . .

But by the beginning of June he was back at his birds in Calcutta—it was more than 100 degrees in his laboratory— and he was asking: "Where do the malaria microbes go from the circles that grow into those big warts in the stomach wall of the mosquito?"